//STARTCOPY
#ifndef _MSC_VER
#include<bits/stdc++.h>
#else
#include <iostream>
#include<algorithm>
#include<vector>
#include <set>
#include <functional>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <assert.h>
#include <queue>
#include <istream>
#include <numeric>
#endif

using namespace std;

using u_counter_type = unsigned int;
using need_int = int;
using counter_type = int;
using MAIN = int;
#define int DontUseIntÉ
using ll = long long;

template<typename T>
using PairOf = pair<T,T>;

using Void = tuple<>;

namespace mytl{

template<typename T, typename R, typename F=function<R(T)> >
vector<R> fmap(F f, const vector<T>& t){
    vector<R> res;
    for(auto elem : t) res.push_back(f(elem));
    return res;
}

template<typename T>
vector<T> forrange(T n, T from){
    vector<T> res(n);
    iota(res.begin(), res.end(), from);
    return res;
}

template<typename F>
void repeat(need_int n, const F& callback){
    for(need_int _ : forrange(n,0)) callback();
}

#define WATCH(x) cout << (#x) << " is " << (x) << endl
}
namespace mytl{

template<typename T>
T discrete_binary_search(function<bool(T)> f, T l, T r){
    if(!f(l)) return l;
    while(l < r){
        T pivot = (l+r)/2;
        if(!f(pivot)) r = pivot-1;
        else if(!f(pivot+1)) l = r = pivot;
        else l = pivot+1;
    }
    return l;
}

template<typename T>
T continuous_binary_search(function<bool(T)> f, T l, T r, need_int iterations){
    mytl::repeat(iterations,[&](){
        T pivot = (l+r)/2;
        if(f(pivot)) l = pivot;
        else r = pivot;
    });
    return l;
}
}
namespace mytl{

template<typename T>
struct LazyVector : vector<T>{
    typename vector<T>::reference operator[](counter_type i){
        if(i >= this->size()) this->resize(i+1);
        return vector<T>::operator[](i);
    }
};

template<typename K, typename T>
struct AssocVector : LazyVector<T>{
    LazyVector<bool> exists;
    typename vector<T>::reference operator[](counter_type i){
        exists[i] = true;
        return LazyVector<T>::operator[](i);
    }
    typename vector<T>::iterator find(counter_type i){
        if(!exists[i]) return this->end();
        else return this->begin() + i;
    }
};

template<template<typename, typename, typename...> typename Container, typename Key, typename Value>
bool has_key(Container<Key, Value>& container, Key key){
    return container.find(key) != container.end();
}

}
namespace mytl{

struct Point{
    ll x, y;

    Point(ll x, ll y) : x{x}, y{y} {};
    Point(pair<ll,ll> initPair) : x{initPair.first}, y{initPair.second} {};

    pair<ll,ll> getPair(){//not introducing type cast operator for safety
        return {x,y};
    }

    //Unary operators
    Point operator-() const{
        return {-x, -y};
    }
    Point operator+() const{
        return {x,y};
    }

    static ll sgn(ll x){
        return (x > 0) - (x < 0);
    }

    //Binary operators on ordinary numbers
    Point operator*(const ll& operand) const{
        return {x*operand, y*operand};
    }

    //Binary operators on Point itself
    Point operator+(const Point& operand) const{
        return {x+operand.x, y+operand.y};
    }
    Point operator-(const Point& operand) const{
        return {x-operand.x, y-operand.y};
    }

    ll operator*(const Point& operand){ //vectorial product
        return x*operand.y - y*operand.x;
    }

    ll direction(const Point& a, const Point& b) const{
        return sgn((a - *this) * (b - *this));
    };
};

ll distance_squared(const Point& a, const Point& b){
    return (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y);
}

double distance(const Point& a, const Point& b){
    return sqrt(distance_squared(a, b));
}

ll cartesian_distance(const Point& a, const Point& b){
    return abs(a.x - b.x) + abs(a.y - b.y);
}

typedef vector<Point> Poly;

bool inside(const Poly& poly, const Point& point, bool strict){ //assuming Poly is weakly convex
    ll prevdir = -2;
    for(ll i=0; i<poly.size(); i++){
        ll nexdindex = (i+1)%poly.size();
        ll dir = poly[i].direction(poly[nexdindex], point);
        if(dir == 0){
            if(strict) return false;
        }
        else{
            if(dir != prevdir && prevdir != -2) return false;
            prevdir = dir;
        }

    }
    return true;
}

}
namespace mytl {

template<class T>
struct Resetter;

template<class T>
Resetter<T>* global_resetter = new Resetter<T>;

template<class T>
struct Resetter {

    using State = pair<counter_type, T>;

    State* state = new State{0, T()};

    Resetter(){}
    Resetter(T value){
        state = new State{0, value};
    }

    void activate(){
        global_resetter<T> = this;
    }

    void reset(T value){
        *state = State{state->first+1, value};
    }

    struct Variable{

        State state;
        State& parent = *global_resetter<T>->state;

        Variable() : state{*global_resetter<T>->state} {}
        Variable(T value) : state{global_resetter<T>->state->first, value} {}
        Variable(State st) : state{st} {}
        Variable(T value, State& parent) : state{parent->first, value} {};

        bool fresh(){
            return state.first >= parent.first;
        }

        void overwrite(){
            state = parent;
        }

        void refresh(){
            if(!fresh()) overwrite();
        }

        T get(){
            refresh();
            return state.second;
        }

        void survive(){
            state.first = parent.first;
        }

        void operator=(T new_value){
            state.second = new_value;
            survive();
        }

    };

};
}

namespace std{

istream& operator>>(istream& is, Void& x){
    return is;
}

template<typename P, typename Q>
istream& operator>>(istream& is, pair<P,Q> x){
    return is>>x.first>>x.second;
}

template<typename P, typename Q>
ostream& operator<<(ostream& os, const pair<P,Q>& x){
    os<<"("<<x.first<<", "<<x.second<<")";
    return os;
}

template<typename T, template<typename, typename...> typename Container>
ostream& operator<<(ostream& os, const Container<T>& x){
    os<<"{";
    bool first = true;
    for(const auto& elem : x){
        if(!first) os<<", ";
        os<<elem;
        first = false;
    }
    os<<"}";
    return os;
}

}

namespace mytl{

template<typename T, typename P=T>
T read(istream& is=cin){
    P a;
    is>>a;
    return T(a);
}

template<typename T, typename P, typename Q>
T read(istream& is=cin){
    P a;
    Q b;
    is>>a>>b;
    return T(a,b);
}

template<typename T, typename P, typename Q, typename R>
T read(istream& is=cin){
    P a;
    Q b;
    R c;
    is>>a>>b>>c;
    return T(a,b,c);
}

template<typename T, typename... Q, typename Container=vector<T>>
vector<T> readValues(ll n, istream& is=cin){
    vector<T> res;
    repeat(n, [&res](){
        res.push_back(read<T,Q...>());
    });
    return Container(res.begin(), res.end());
}

}

namespace mytl{

template<typename T>
void print(const T& x, ostream& os=cout){
    os<<x;
}

}
namespace mytl{
template<typename T>
T power(T base, ll exponential, T unit=1){
    T res = unit;
    while(exponential > 0){
        if(exponential%2 == 1) res = res * base;
        base = base * base;
        exponential = exponential / 2;
    }
    return res;
}
}
namespace mytl{
    struct Modulo{
        static ll global_mod;
    private:
        ll val;
    public:
        const ll MOD;
        Modulo(ll initMOD, ll initVal) : MOD{initMOD}, val{initVal} {
            val %= MOD;
            if(val < 0) val += MOD;
        };
        Modulo() : Modulo(global_mod, 0) {};

        static Modulo inverse(Modulo x){// asserting MOD is prime
            return power(x, x.MOD-2, x.unit());
        };
        Modulo unit() const{
            return Modulo(MOD, 1);
        }
        Modulo& operator=(const Modulo& operand){
            val = operand.val;
            return *this;
        };

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        Modulo operator-() const{
            return Modulo(MOD, -val);
        };
        Modulo operator+() const{
            return Modulo(MOD, +val);
        };

        //Binary operators on ordinary numbers
        Modulo operator-(const ll& operand) const{
            return Modulo(MOD, val-operand);
        };
        Modulo operator+(const ll& operand) const{
            return Modulo(MOD, val+operand);
        };
        Modulo operator*(const ll& operand) const{
            return Modulo(MOD, val*operand);
        };
        Modulo operator/(const ll& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(Modulo(MOD, operand)).get());
        };

        //Binary operators on Modulo
        Modulo operator-(const Modulo& operand) const{
            return Modulo(MOD, val-operand.get());
        };
        Modulo operator+(const Modulo& operand) const{
            return Modulo(MOD, val+operand.get());
        };
        Modulo operator*(const Modulo& operand) const{
            return Modulo(MOD, val*operand.get());
        };
        Modulo operator/(const Modulo& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(operand).get());
        };

    };

    ll Modulo::global_mod = 1000000007LL;

    Modulo mod107(ll x){
        return Modulo(1000000007LL, x);
    }
    ostream& operator<<(ostream& os, Modulo x){
        return os<<"("<<x.get()<<"%"<<x.MOD<<")";
    }

}
namespace mytl{
    template<ll MOD>
    struct TSModulo{
    private:
        ll val;

    public:
        static TSModulo inverse(TSModulo x){// asserting MOD is prime
            return power(x, MOD-2);
        };
        TSModulo(ll initVal) : val{(MOD + initVal%MOD)%MOD} {};
        TSModulo() : TSModulo(0) {}
        TSModulo& operator=(const TSModulo&) = default;

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        TSModulo operator-() const{
            return TSModulo(-val);
        };
        TSModulo operator+() const{
            return TSModulo(+val);
        };

        //Binary operators on ordinary numbers
        TSModulo operator-(const ll& operand) const{
            return TSModulo(val-operand);
        };
        TSModulo operator+(const ll& operand) const{
            return TSModulo(val+operand);
        };
        TSModulo operator*(const ll& operand) const{
            return TSModulo(val*operand);
        };
        TSModulo operator/(const ll& operand) const{ //asserting MOD is prime
            return TSModulo(inverse(operand) * val);
        };

        //Binary operators on Modulo
        TSModulo operator-(const TSModulo& operand) const{
            return TSModulo(val-operand.get());
        };
        TSModulo operator+(const TSModulo& operand) const{
            return TSModulo(val+operand.get());
        };
        TSModulo operator*(const TSModulo& operand) const{
            return TSModulo(val*operand.get());
        };
        TSModulo operator/(const TSModulo& operand) const{ //asserting MOD is prime
            return TSModulo(val * inverse(operand));
        };
    };

    using Mod107 = TSModulo<1000000007LL>;

    template<ll MOD>
    ostream& operator<<(ostream& os, TSModulo<MOD> x){
        return os<<"("<<x.get()<<"%"<<MOD<<")";
    }

}
namespace mytl{

template <template<typename, typename, typename...> typename C, typename Arg, typename R>
function<R (Arg)> memoize(R (*fn)(Arg)) {
    C<Arg, R* > table;
    return [fn, table](Arg arg) mutable -> R {
        R*& res = table[arg];
        if(res == nullptr){
			res = new R;
			*res = fn(arg);
        }
		return *res;
    };
}

}
namespace mytl{
template<class Op>
struct Node : Op::Range{
    using Range = typename Op::Range;
    using T = typename Op::T;
    using Change = typename Op::Change;
    using Range::singleton;
    using Range::inside;
    using Range::intersect;
    using Range::leftHalf;
    using Range::rightHalf;

    Node *left_child=NULL, *right_child=NULL;

    T partial;
    Change pending = Op::identity();

    Node(Range range) : Range(range), partial{Op::initial(range)} {};

    T query(Range range, Change change){
        return query_(range, change).first;
    }

    void add(Change change){
        pending = Op::push(pending, change);
    }

    void prepare(){
        if(!singleton()){
            if(left_child == NULL) left_child = (new Node(leftHalf()));
            if(right_child == NULL) right_child = (new Node(rightHalf()));
            left_child->add(pending);
            right_child->add(pending);
        }
        partial = Op::apply(*this, partial, pending);
        pending = Op::identity();
    }

    pair<T,T> query_(Range range, Change change){
        //cout<<range<<" "<<*this<<endl;
        prepare();
        if(inside(range)){
            add(change);
            prepare();
            return {partial, Op::zero()};
        }
        if(!intersect(range)){
            //cout<<"n"<<range<<" "<<*this<<endl;
            return {Op::zero(), partial};
        }

        auto from_left = left_child->query_(range, change);
        auto from_right = right_child->query_(range, change);
        //cout<<from_right.first<<endl;
        auto needed = Op::reduce(from_left.first, from_right.first), rest = Op::reduce(from_left.second, from_right.second);
        partial = Op::reduce(needed, rest);
        return {needed, rest};
    }

    T build_from(const function<T(ll)>& getter){
        prepare();
        pending = Op::identity();
        if(singleton()) partial = getter(this->l);
        else partial = Op::reduce(left_child->build_from(getter), right_child->build_from(getter));
        return partial;
    }

};

struct Range1D{

    ll l, r;

    Range1D(ll l, ll r): l{l}, r{r} {}

    ll span() const {
        return r-l+1;
    }
    bool singleton() const {
        return span() == 1;
    }
    Range1D leftHalf() const {
        return Range1D(l, (l+r)/2);
    }
    Range1D rightHalf() const {
        return Range1D((l + r)/2 + 1, r);
    }
    bool inside(const Range1D& other) const {
        return other.l <= l && r <= other.r;
    }
    bool intersect(const Range1D& other) const {

        return other.inside(*this)
             ||(other.l <= l && l <= other.r)
             ||(other.l <= r && r <= other.r);
    }
};

}

namespace mytl{
template<typename T_>
struct Add_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 0;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return zero();
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a + r.span()*c;
    }

    static Change push(Change a, Change b){
        return a + b;
    }
};

template<typename T_>
struct Multiply_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 1;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return r.span()*1;
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a*c;
    }

    static Change push(Change a, Change b){
        return a*b;
    }
};

}

namespace mytl{
/*
struct Custom_Op{
    using Range = _;
    using T = _;
    using Change = _;

    static Change identity(){
        return _;
    }

    static T zero(){
        return _;
    }

    static T initial(Range r){
        return _;
    }

    static T reduce(T a, T b){
        return _;
    }

    static T apply(Range r, T a, Change c){
        return _;
    }

    static Change push(Change a, Change b){
        return _;
    }

};
*/

}
namespace mytl{

template<typename T, T(*f)(T,T)>
struct Tracker {

	T* val = nullptr;

    void update(T x){
        if(val != nullptr){
            *val = f(*val, x);
        }
        else{
			val = new T;
			*val = x;
        }
    }

	T value() {
		return *val;
	}
};

template<typename T>
T min(T a, T b){return std::min(a,b);}
template<typename T>
T max(T a, T b){return std::max(a,b);}
template<typename T>
T __gcd(T a, T b){return std::__gcd(a,b);}

}
//ENDCOPY

using G = mytl::Container_Graph<ll, Void, mytl::AssocVector>;

void processs(){
    ll n;
    cin>>n;
    G g(n);
    mytl::readEdgeList(g, n-1);

        //cout<<"hh";
    auto enyem_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> enyem(enyem_.begin(), enyem_.end());
    auto ove_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> ove(ove_.begin(), ove_.end());

    //cout<<enyem<<" "<<ove<<endl;
    auto ask = [&](ll& ide, char tipus, ll ki) -> bool{
        cout<<tipus<<" "<<ki<<endl;
        ll got;
        cin>>got;
        if(tipus == 'A' && mytl::has_key(ove, got)){
            cout<<"C "<<ki<<endl;
            return true;
        }
        if(tipus == 'B' && mytl::has_key(enyem, got)){
            cout<<"C "<<got<<endl;
            return true;
        }
        ide = got;
        return false;

    };

    ll one_piece;
    if(ask(one_piece, 'B', *ove.begin())) return;
     vector<pair<pair<ll,ll>, ll> > sour{{{0,-1}, *enyem.begin()}};
    // cout<<sour<<endl;
   auto tb = mytl::queue_graph_algorithm<G, mytl::AlgoComposer<mytl::FILO,mytl::SimpleLengthAndLastNode>::A >(g,sour);

    while(!mytl::has_key(enyem, one_piece)){
        one_piece = tb[one_piece].second;
    }

    ll dc;
    if(ask(dc, 'A', one_piece)) return;
    else{
        cout<<"C -1"<<endl;
    }

}

MAIN main(){
    ll T;
    cin>>T;
    mytl::repeat(T, [&](){
        processs();
    }) ;
}


//STARTCOPY
#include<bits/stdc++.h>
using namespace std;

using u_counter_type = unsigned int;
using need_int = int;
using counter_type = int;
using MAIN = int;
#define int DontUseIntÉ
using ll = long long;

template<typename T>
using PairOf = pair<T,T>;

using Void = tuple<>;

struct BasicInitialization{
    BasicInitialization(){
        ios_base::sync_with_stdio(false);
    }
};
BasicInitialization __basic_initialization__;
namespace mytl{

template<typename T, typename R, typename F=function<R(T)> >
vector<R> fmap(F f, const vector<T>& t){
    vector<R> res;
    for(auto elem : t) res.push_back(f(elem));
    return res;
}

template<typename T>
vector<T> forrange(T n, T from){
    vector<T> res(n);
    iota(res.begin(), res.end(), from);
    return res;
}

template<typename F>
void repeat(need_int n, const F& callback){
    for(need_int _ : forrange(n,0)) callback();
}

template<typename T, template<typename, typename...> typename Container>
vector<PairOf<T&> > adjecent_pairs(Container<T>& c){
    vector<PairOf<T&> > res;
    optional<T*> prev_elem;
    for(auto& elem : c){
        if(prev_elem.has_value()){
            res.push_back({*prev_elem.value(), elem});
        }
        prev_elem = &elem;
    }
    return res;
}
#define WATCH(x) cout << (#x) << " is " << (x) << endl
}
namespace mytl{

template<typename T>
T discrete_binary_search(function<bool(T)> f, T l, T r){
    if(!f(l)) return l;
    while(l < r){
        T pivot = (l+r)/2;
        if(!f(pivot)) r = pivot-1;
        else if(!f(pivot+1)) l = r = pivot;
        else l = pivot+1;
    }
    return l;
}

template<typename T>
T continuous_binary_search(function<bool(T)> f, T l, T r, need_int iterations){
    mytl::repeat(iterations,[&](){
        T pivot = (l+r)/2;
        if(f(pivot)) l = pivot;
        else r = pivot;
    });
    return l;
}
}
namespace mytl{

template<typename T>
struct LazyVector : vector<T>{
    typename vector<T>::reference operator[](counter_type i){
        if(i >= this->size()) this->resize(i+1);
        return vector<T>::operator[](i);
    }
};

template<typename K, typename T>
struct AssocVector : LazyVector<T>{
    LazyVector<bool> exists;
    typename vector<T>::reference operator[](counter_type i){
        exists[i] = true;
        return LazyVector<T>::operator[](i);
    }
    typename vector<T>::iterator find(counter_type i){
        if(!exists[i]) return this->end();
        else return this->begin() + i;
    }
};

template<template<typename, typename, typename...> typename Container, typename Key, typename Value>
bool has_key(Container<Key, Value>& container, Key key){
    return container.find(key) != container.end();
}

}
namespace mytl{

struct Point{
    ll x, y;

    Point(ll x, ll y) : x{x}, y{y} {};
    Point(pair<ll,ll> initPair) : x{initPair.first}, y{initPair.second} {};

    pair<ll,ll> getPair(){//not introducing type cast operator for safety
        return {x,y};
    }

    //Unary operators
    Point operator-() const{
        return {-x, -y};
    }
    Point operator+() const{
        return {x,y};
    }

    static ll sgn(ll x){
        return (x > 0) - (x < 0);
    }

    //Binary operators on ordinary numbers
    Point operator*(const ll& operand) const{
        return {x*operand, y*operand};
    }

    //Binary operators on Point itself
    Point operator+(const Point& operand) const{
        return {x+operand.x, y+operand.y};
    }
    Point operator-(const Point& operand) const{
        return {x-operand.x, y-operand.y};
    }

    ll operator*(const Point& operand){ //vectorial product
        return x*operand.y - y*operand.x;
    }

    ll direction(const Point& a, const Point& b) const{
        return sgn((a - *this) * (b - *this));
    };
};

ll distance_squared(const Point& a, const Point& b){
    return (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y);
}

double distance(const Point& a, const Point& b){
    return sqrt(distance_squared(a, b));
}

ll cartesian_distance(const Point& a, const Point& b){
    return abs(a.x - b.x) + abs(a.y - b.y);
}

typedef vector<Point> Poly;

bool inside(const Poly& poly, const Point& point, bool strict){ //assuming Poly is weakly convex
    ll prevdir = -2;
    for(ll i=0; i<poly.size(); i++){
        ll nexdindex = (i+1)%poly.size();
        ll dir = poly[i].direction(poly[nexdindex], point);
        if(dir == 0){
            if(strict) return false;
        }
        else{
            if(dir != prevdir && prevdir != -2) return false;
            prevdir = dir;
        }

    }
    return true;
}

}

namespace std{

template<typename T>
istream& operator>>(istream& is, optional<T>& x){
    if(!x.has_value()){
        T x_;
        is>>x_;
        x = x_;
    }
    return is;
}

istream& operator>>(istream& is, Void& x){
    return is;
}

template<typename P, typename Q>
istream& operator>>(istream& is, pair<P,Q> x){
    return is>>x.first>>x.second;
}

template<typename P, typename Q>
ostream& operator<<(ostream& os, const pair<P,Q>& x){
    os<<"("<<x.first<<", "<<x.second<<")";
    return os;
}

template<typename T, template<typename, typename...> typename Container>
ostream& operator<<(ostream& os, const Container<T>& x){
    os<<"{";
    bool first = true;
    for(const auto& elem : x){
        if(!first) os<<", ";
        os<<elem;
        first = false;
    }
    os<<"}";
    return os;
}

}

namespace mytl{

template<typename T, typename P=T>
T read(istream& is=cin){
    P a;
    is>>a;
    return T(a);
}

template<typename T, typename P, typename Q>
T read(istream& is=cin){
    P a;
    Q b;
    is>>a>>b;
    return T(a,b);
}

template<typename T, typename P, typename Q, typename R>
T read(istream& is=cin){
    P a;
    Q b;
    R c;
    is>>a>>b>>c;
    return T(a,b,c);
}

template<typename T, typename... Q, typename Container=vector<T>>
vector<T> readValues(ll n, istream& is=cin){
    vector<T> res;
    repeat(n, [&res](){
        res.push_back(read<T,Q...>());
    });
    return Container(res.begin(), res.end());
}

}

namespace mytl{

template<typename T>
void print(const T& x, ostream& os=cout){
    os<<x;
}

}
namespace mytl{

template<typename N, typename E, template<typename, typename, typename...> typename C>
struct Container_Graph{
    template<typename A, typename B>
    using Container = C<A,B>;
    using Edge = E;
    using Node = N;
    struct Arm{
        Edge edge;
        Node node;
    };

    Container<Node,  vector<Arm> > container;

    optional<ll> n;
    Container_Graph(ll n={}) : n{n}, container() {}

    void newEdge(Node u, Node v, Edge edge=Void()){
        container[u].push_back({edge, v});
    }
    vector<Node> getNodes(){
        vector<Node> res;
        if(n.has_value()){
            for(ll i=1; i<=n.value(); i++) res.push_back(i);
        }
        else{
            for(auto& p : container){
                res.push_back(p.first);
            }
        }
        return res;

    }
    vector<Arm >& getEdges(Node node){
        return container[node];
    }
    vector<Node > getNeighbours(Node node){
        vector<Node> res;
        for(auto& arm : getEdges(node)){
            res.push_back(arm.node);
        }
        return res;
    }

};

using NormalSimpleGraph = Container_Graph<ll, Void, AssocVector>;

template<typename G>
void readNeighbourList(G& g, ll indexing=1){
    for(ll i : forrange(g.n.size(), indexing)){
        for(ll neig : readValues<ll>(read<ll>())){
            g.new_edge(i, neig);
        }
    }
}

template<typename G>
void readEdgeList(G& g, ll m, bool bidirectional=true){
    using Node = typename G::Node;
    using Edge = typename G::Edge;
    for(auto elem : readValues<tuple<Node, Node, Edge>, Node, Node, Edge >(m)){
        Node u, v;
        Edge edge;
        tie(u, v, edge) = elem;
        g.newEdge(u,v,edge);
        if(bidirectional) g.newEdge(v, u, edge);
    }
}

template<typename G, template<typename> typename Path>
struct Reaching{
    typename Path<G>::Info info;
    typename G::Node node;
    bool operator<(const Reaching& other) const {
        return info > other.info;
    }
};

template<
    typename G,
    template<typename> typename QP,
    template<typename> typename P,
    typename F=void(*)(typename P<G>::Info, typename G::Node)
>
typename G::template Container<typename G::Node, typename P<G>::Info> queue_graph_algorithm(
    G& g,
    vector<Reaching<G,P> > sources,
    F new_node_callback=[](typename P<G>::Info, typename G::Node){})
{

    using Path = P<G>;
    using Edge = typename G::Edge;
    using Node = typename G::Node;
    using Info = typename Path::Info;
    //using Option = pair<Info, Node>;
    using R = Reaching<G,P>;
    using QueuePolicy = QP<R>;
    using Queue = typename QueuePolicy::Queue;

    Queue q;
    for(R source : sources) QueuePolicy::push(q, source);
    typename G::template Container<Node, Info> d;
    while(!q.empty()){
        R akt = QueuePolicy::consume(q);

        if(has_key(d, akt.node)) continue;

        d[akt.node] = akt.info;

        new_node_callback(akt.info, akt.node);
        for(auto arm : g.getEdges(akt.node)) if(!has_key(d, arm.node)){
            QueuePolicy::push(q, {Path::append(akt.info, akt.node, arm.edge, arm.node), arm.node});
        }
    }
    return d;
}

template<
        typename G,
        template<typename> typename QP,
        template<typename> typename P,
        typename F=void(*)(typename P<G>::Info, typename G::Node)
>
typename G::template Container<typename G::Node, typename P<G>::Info> queue_graph_algorithm_from_single_source(
        G& g,
        typename P<G>::Info info,
        typename G::Node node,
        F new_node_callback=[](typename P<G>::Info, typename G::Node){})
{
    return queue_graph_algorithm<G,QP,P,F>(g, {{info,node}},new_node_callback);
}

template<typename T>
struct Priority{
    using Queue = priority_queue<T>;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FIFO{
    using Queue = queue<T>;
    static T consume(Queue& q){
        auto res = q.front();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FILO{
    using Queue = stack<T>;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.pop();
    }
};

template<typename G>
struct JustLength{
    using Info = typename G::Edge;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return old_info + e;
    }
};

template<typename G>
struct SimpleJustLength{
    using Info = ll;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return old_info + 1;
    }
};

template<typename G>
struct LengthAndLastNode{
    using Info = pair<ll, typename G::Node>;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return {old_info + e, old_node};
    }
};

template<typename G>
struct SimpleLengthAndLastNode{
    using Info = pair<typename G::Edge, typename G::Node>;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return {old_info + 1, old_node};
    }
};

}
namespace mytl {

template<class T>
struct Resetter;

template<class T>
Resetter<T>* global_resetter = new Resetter<T>;

template<class T>
struct Resetter {

    using State = pair<counter_type, T>;

    State* state = new State{0, T()};

    Resetter(){}
    Resetter(T value){
        state = new State{0, value};
    }

    void activate(){
        global_resetter<T> = this;
    }

    void reset(T value){
        *state = State{state->first+1, value};
    }

    struct Variable{

        State state;
        State& parent = *global_resetter<T>->state;

        Variable() : state{*global_resetter<T>->state} {}
        Variable(T value) : state{global_resetter<T>->state->first, value} {}
        Variable(State st) : state{st} {}
        Variable(T value, State& parent) : state{parent->first, value} {};

        bool fresh(){
            return state.first >= parent.first;
        }

        void overwrite(){
            state = parent;
        }

        bool refresh(){
            if(!fresh()) overwrite();
        }

        T get(){
            refresh();
            return state.second;
        }

        void survive(){
            state.first = parent.first;
        }

        void operator=(T new_value){
            state.second = new_value;
            survive();
        }

    };

};
}
namespace mytl{

template<typename T>
struct Lazy : optional<T>{

    function<T()> f;

    Lazy(function<T()> f) : f{f}, optional<T>() {};

    T& value(){
        if(!this->has_value()){
            optional<T>::operator=(f());
        }
        return optional<T>::value();
    }

};

#define LAZY(val, tipe) mytl::Lazy<tipe>([&](){return (val);})

}
namespace mytl{
template<typename T>
T power(T base, ll exponential, T unit=1){
    T res = unit;
    while(exponential > 0){
        if(exponential%2 == 1) res = res * base;
        base = base * base;
        exponential = exponential / 2;
    }
    return res;
}
}
namespace mytl{
    struct Modulo{
        static ll global_mod;
    private:
        ll val;
    public:
        const ll MOD;
        Modulo(ll initMOD, ll initVal) : MOD{initMOD}, val{initVal} {
            val %= MOD;
            if(val < 0) val += MOD;
        };
        Modulo() : Modulo(global_mod, 0) {};

        static Modulo inverse(Modulo x){// asserting MOD is prime
            return power(x, x.MOD-2, x.unit());
        };
        Modulo unit() const{
            return Modulo(MOD, 1);
        }
        Modulo& operator=(const Modulo& operand){
            val = operand.val;
            return *this;
        };

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        Modulo operator-() const{
            return Modulo(MOD, -val);
        };
        Modulo operator+() const{
            return Modulo(MOD, +val);
        };

        //Binary operators on ordinary numbers
        Modulo operator-(const ll& operand) const{
            return Modulo(MOD, val-operand);
        };
        Modulo operator+(const ll& operand) const{
            return Modulo(MOD, val+operand);
        };
        Modulo operator*(const ll& operand) const{
            return Modulo(MOD, val*operand);
        };
        Modulo operator/(const ll& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(Modulo(MOD, operand)).get());
        };

        //Binary operators on Modulo
        Modulo operator-(const Modulo& operand) const{
            return Modulo(MOD, val-operand.get());
        };
        Modulo operator+(const Modulo& operand) const{
            return Modulo(MOD, val+operand.get());
        };
        Modulo operator*(const Modulo& operand) const{
            return Modulo(MOD, val*operand.get());
        };
        Modulo operator/(const Modulo& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(operand).get());
        };

    };

    ll Modulo::global_mod = 1000000007LL;

    Modulo mod107(ll x){
        return Modulo(1000000007LL, x);
    }
    ostream& operator<<(ostream& os, Modulo x){
        return os<<"("<<x.get()<<"%"<<x.MOD<<")";
    }

}
namespace mytl{
    template<ll MOD>
    struct TSModulo{
    private:
        ll val;

    public:
        static TSModulo inverse(TSModulo x){// asserting MOD is prime
            return power(x, MOD-2);
        };
        TSModulo(ll initVal) : val{(MOD + initVal%MOD)%MOD} {};
        TSModulo() : TSModulo(0) {}
        TSModulo& operator=(const TSModulo&) = default;

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        TSModulo operator-() const{
            return TSModulo(-val);
        };
        TSModulo operator+() const{
            return TSModulo(+val);
        };

        //Binary operators on ordinary numbers
        TSModulo operator-(const ll& operand) const{
            return TSModulo(val-operand);
        };
        TSModulo operator+(const ll& operand) const{
            return TSModulo(val+operand);
        };
        TSModulo operator*(const ll& operand) const{
            return TSModulo(val*operand);
        };
        TSModulo operator/(const ll& operand) const{ //asserting MOD is prime
            return TSModulo(inverse(operand) * val);
        };

        //Binary operators on Modulo
        TSModulo operator-(const TSModulo& operand) const{
            return TSModulo(val-operand.get());
        };
        TSModulo operator+(const TSModulo& operand) const{
            return TSModulo(val+operand.get());
        };
        TSModulo operator*(const TSModulo& operand) const{
            return TSModulo(val*operand.get());
        };
        TSModulo operator/(const TSModulo& operand) const{ //asserting MOD is prime
            return TSModulo(val * inverse(operand));
        };
    };

    using Mod107 = TSModulo<1000000007LL>;

    template<ll MOD>
    ostream& operator<<(ostream& os, TSModulo<MOD> x){
        return os<<"("<<x.get()<<"%"<<MOD<<")";
    }

}
namespace mytl{

template <template<typename, typename, typename...> typename C, typename Arg, typename R>
function<R (Arg)> memoize(R (*fn)(Arg)) {
    C<Arg, optional<R> > table;
    return [fn, table](Arg arg) mutable -> R {
        optional<R>& res = table[arg];
        if(!res.has_value()){
            res = fn(arg);
        }
        return res.value();
    };
}

}
namespace mytl{
template<class Op>
struct Node : Op::Range{
    using Range = typename Op::Range;
    using T = typename Op::T;
    using Change = typename Op::Change;
    using Range::singleton;
    using Range::inside;
    using Range::intersect;
    using Range::leftHalf;
    using Range::rightHalf;

    Node *left_child=NULL, *right_child=NULL;

    T partial;
    Change pending = Op::identity();

    Node(Range range) : Range(range), partial{Op::initial(range)} {};

    T query(Range range, Change change){
        return query_(range, change).first;
    }

    void add(Change change){
        pending = Op::push(pending, change);
    }

    void prepare(){
        if(!singleton()){
            if(left_child == NULL) left_child = (new Node(leftHalf()));
            if(right_child == NULL) right_child = (new Node(rightHalf()));
            left_child->add(pending);
            right_child->add(pending);
        }
        partial = Op::apply(*this, partial, pending);
        pending = Op::identity();
    }

    pair<T,T> query_(Range range, Change change){
        //cout<<range<<" "<<*this<<endl;
        prepare();
        if(inside(range)){
            add(change);
            prepare();
            return {partial, Op::zero()};
        }
        if(!intersect(range)){
            //cout<<"n"<<range<<" "<<*this<<endl;
            return {Op::zero(), partial};
        }

        auto from_left = left_child->query_(range, change);
        auto from_right = right_child->query_(range, change);
        //cout<<from_right.first<<endl;
        auto needed = Op::reduce(from_left.first, from_right.first), rest = Op::reduce(from_left.second, from_right.second);
        partial = Op::reduce(needed, rest);
        return {needed, rest};
    }

    T build_from(const function<T(ll)>& getter){
        prepare();
        pending = Op::identity();
        if(singleton()) partial = getter(this->l);
        else partial = Op::reduce(left_child->build_from(getter), right_child->build_from(getter));
        return partial;
    }

};

struct Range1D{

    ll l, r;

    Range1D(ll l, ll r): l{l}, r{r} {}

    ll span() const {
        return r-l+1;
    }
    bool singleton() const {
        return span() == 1;
    }
    Range1D leftHalf() const {
        return Range1D(l, (l+r)/2);
    }
    Range1D rightHalf() const {
        return Range1D((l + r)/2 + 1, r);
    }
    bool inside(const Range1D& other) const {
        return other.l <= l && r <= other.r;
    }
    bool intersect(const Range1D& other) const {

        return other.inside(*this)
             ||(other.l <= l && l <= other.r)
             ||(other.l <= r && r <= other.r);
    }
};

}

namespace mytl{
template<typename T_>
struct Add_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 0;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return zero();
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a + r.span()*c;
    }

    static Change push(Change a, Change b){
        return a + b;
    }
};

template<typename T_>
struct Multiply_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 1;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return r.span()*1;
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a*c;
    }

    static Change push(Change a, Change b){
        return a*b;
    }
};

}

namespace mytl{
/*
struct Custom_Op{
    using Range = _;
    using T = _;
    using Change = _;

    static Change identity(){
        return _;
    }

    static T zero(){
        return _;
    }

    static T initial(Range r){
        return _;
    }

    static T reduce(T a, T b){
        return _;
    }

    static T apply(Range r, T a, Change c){
        return _;
    }

    static Change push(Change a, Change b){
        return _;
    }

};
*/

}
namespace mytl{

template<typename T, T(*f)(T,T)>
struct Tracker : optional<T>{

    Tracker() : optional<T>() {};

    void update(T val){
        if(this->has_value()){
            optional<T>::operator=(f(this->value(), val));
        }
        else{
            optional<T>::operator=(val);
        }
    }
};

template<typename T>
T min(T a, T b){return std::min(a,b);}
template<typename T>
T max(T a, T b){return std::max(a,b);}
template<typename T>
T __gcd(T a, T b){return std::__gcd(a,b);}

}
//ENDCOPY

using G = mytl::Container_Graph<ll, Void, mytl::AssocVector>;

void processs(){
    ll n;
    cin>>n;
    G g(n);
    mytl::readEdgeList(g, n-1);

        //cout<<"hh";
    auto enyem_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> enyem(enyem_.begin(), enyem_.end());
    auto ove_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> ove(ove_.begin(), ove_.end());

    //cout<<enyem<<" "<<ove<<endl;
    auto ask = [&](ll& ide, char tipus, ll ki) -> bool{
        cout<<tipus<<" "<<ki<<endl;
        ll got;
        cin>>got;
        if(tipus == 'A' && mytl::has_key(ove, got)){
            cout<<"C "<<ki<<endl;
            return true;
        }
        if(tipus == 'B' && mytl::has_key(enyem, got)){
            cout<<"C "<<got<<endl;
            return true;
        }
        ide = got;
        return false;

    };

    ll one_piece;
    if(ask(one_piece, 'B', *ove.begin())) return;
     vector<pair<pair<ll,ll>, ll> > sour{{{0,-1}, *enyem.begin()}};
    // cout<<sour<<endl;
   auto tb = mytl::queue_graph_algorithm<G, mytl::AlgoComposer<mytl::FILO,mytl::SimpleLengthAndLastNode>::A >(g,sour);

    while(!mytl::has_key(enyem, one_piece)){
        one_piece = tb[one_piece].second;
    }

    ll dc;
    if(ask(dc, 'A', one_piece)) return;
    else{
        cout<<"C -1"<<endl;
    }

}

MAIN main(){
    ll T;
    cin>>T;
    mytl::repeat(T, [&](){
        processs();
    }) ;
}


//STARTCOPY
#include<bits/stdc++.h>
using namespace std;

using u_counter_type = unsigned int;
using need_int = int;
using counter_type = int;
using MAIN = int;
#define int DontUseIntÉ
using ll = long long;

template<typename T>
using PairOf = pair<T,T>;

using Void = tuple<>;

struct BasicInitialization{
    BasicInitialization(){
        ios_base::sync_with_stdio(false);
    }
};
BasicInitialization __basic_initialization__;
namespace mytl{

    template<typename T, typename R, typename F=function<R(T)> >
    vector<R> fmap(F f, const vector<T>& t){
        vector<R> res;
        for(auto elem : t) res.push_back(f(elem));
        return res;
    }

    template<typename T>
    vector<T> forrange(T n, T from){
        vector<T> res(n);
        iota(res.begin(), res.end(), from);
        return res;
    }

    template<typename F>
    void repeat(need_int n, const F& callback){
        for(need_int _ : forrange(n,0)) callback();
    }

    template<typename T>
    struct optional{
    private:
        T *val = nullptr;
        void reserve(){
            val = new T;
        }
    public:
        optional<T> operator=(const T& operand){
            reserve();
            *val = operand;
            return *this;
        }
        bool has_value(){
            return val != nullptr;
        }
        T& value(){
            return *val;
        }
        optional(T val_){
            operator=(val_);
        }
        optional(initializer_list<T> l){
            assert(l.size() == 1);
            operator=(*l.begin());
        }
        optional(){}
    };

    template<typename T>
    optional<T> make_optional(T val_){
        return optional<T>(val_);
    }

    template<typename T, T(*f)(T,T)>
    struct Tracker : optional<T>{
        using optional<T>::operator=;

        Tracker() : optional<T>() {};

        void update(T val){
            if(this->has_value()){
                *this = f(this->value(), val);
            }
            else{
                *this = val;
            }
        }
    };

    template<typename T>
    T min(T a, T b){return std::min(a,b);}
    template<typename T>
    T max(T a, T b){return std::max(a,b);}
    template<typename T>
    T __gcd(T a, T b){return std::__gcd(a,b);}

    template<typename T, template<typename, typename...> typename Container>
    vector<PairOf<T&> > adjecent_pairs(Container<T>& c){
        vector<PairOf<T&> > res;
        optional<T*> prev_elem;
        for(auto& elem : c){
            if(prev_elem.has_value()){
                res.push_back({*prev_elem.value(), elem});
            }
            prev_elem = &elem;
        }
        return res;
    }

    template<typename T>
    struct LazyVector : vector<T>{
        typename vector<T>::reference operator[](counter_type i){
            if(i >= this->size()) this->resize(i+1);
            return vector<T>::operator[](i);
        }
    };

    template<typename K, typename T>
    struct AssocVector : LazyVector<T>{
        LazyVector<bool> exists;
        typename vector<T>::reference operator[](counter_type i){
            exists[i] = true;
            return LazyVector<T>::operator[](i);
        }
        typename vector<T>::iterator find(counter_type i){
            if(!exists[i]) return this->end();
            else return this->begin() + i;
        }
    };

    template<template<typename, typename, typename...> typename Container, typename Key, typename Value>
    bool has_key(Container<Key, Value>& container, Key key){
        return container.find(key) != container.end();
    }

    template<typename T>
    struct Lazy : optional<T>{

        function<T()> f;

        Lazy(function<T()> f) : f{f}, optional<T>() {};

        T& value(){
            if(!this->has_value()){
                optional<T>::operator=(f());
            }
            return optional<T>::value();
        }

    };

#define LAZY(val, tipe) mytl::Lazy<tipe>([&](){return (val);})
#define WATCH(x) cout << (#x) << " is " << (x) << endl
}
namespace mytl{

    template<typename T>
    T discrete_binary_search(function<bool(T)> f, T l, T r){
        if(!f(l)) return l;
        while(l < r){
            T pivot = (l+r)/2;
            if(!f(pivot)) r = pivot-1;
            else if(!f(pivot+1)) l = r = pivot;
            else l = pivot+1;
        }
        return l;
    }

    template<typename T>
    T continuous_binary_search(function<bool(T)> f, T l, T r, need_int iterations){
        mytl::repeat(iterations,[&](){
            T pivot = (l+r)/2;
            if(f(pivot)) l = pivot;
            else r = pivot;
        });
        return l;
    }
}

namespace std{

    template<typename T>
    istream& operator>>(istream& is, mytl::optional<T>& x){
        if(!x.has_value()){
            T x_;
            is>>x_;
            x = x_;
        }
        return is;
    }

    istream& operator>>(istream& is, Void& x){
        return is;
    }

    template<typename P, typename Q>
    istream& operator>>(istream& is, pair<P,Q> x){
        return is>>x.first>>x.second;
    }

    template<typename P, typename Q>
    ostream& operator<<(ostream& os, const pair<P,Q>& x){
        os<<"("<<x.first<<", "<<x.second<<")";
        return os;
    }

    template<typename T, template<typename, typename...> typename Container>
    ostream& operator<<(ostream& os, const Container<T>& x){
        os<<"{";
        bool first = true;
        for(const auto& elem : x){
            if(!first) os<<", ";
            os<<elem;
            first = false;
        }
        os<<"}";
        return os;
    }

}

namespace mytl{

    template<typename T, typename P=T>
    T read(istream& is=cin){
        P a;
        is>>a;
        return T(a);
    }

    template<typename T, typename P, typename Q>
    T read(istream& is=cin){
        P a;
        Q b;
        is>>a>>b;
        return T(a,b);
    }

    template<typename T, typename P, typename Q, typename R>
    T read(istream& is=cin){
        P a;
        Q b;
        R c;
        is>>a>>b>>c;
        return T(a,b,c);
    }

    template<typename T, typename... Q, typename Container=vector<T>>
    vector<T> readValues(ll n, istream& is=cin){
        vector<T> res;
        repeat(n, [&res](){
            res.push_back(read<T,Q...>());
        });
        return Container(res.begin(), res.end());
    }

}

namespace mytl{

    template<typename T>
    void print(const T& x, ostream& os=cout){
        os<<x;
    }

}
namespace mytl{
    template<typename T>
    T power(T base, ll exponential, T unit=1){
        T res = unit;
        while(exponential > 0){
            if(exponential%2 == 1) res = res * base;
            base = base * base;
            exponential = exponential / 2;
        }
        return res;
    }
}
namespace mytl{
    template<ll MOD>
    struct TSModulo{
    private:
        ll val;

    public:
        static TSModulo inverse(TSModulo x){// asserting MOD is prime
            return power(x, MOD-2);
        };
        TSModulo(ll initVal) : val{(MOD + initVal%MOD)%MOD} {};
        TSModulo() : TSModulo(0) {}
        TSModulo& operator=(const TSModulo&) = default;

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        TSModulo operator-() const{
            return TSModulo(-val);
        };
        TSModulo operator+() const{
            return TSModulo(+val);
        };

        //Binary operators on ordinary numbers
        TSModulo operator-(const ll& operand) const{
            return TSModulo(val-operand);
        };
        TSModulo operator+(const ll& operand) const{
            return TSModulo(val+operand);
        };
        TSModulo operator*(const ll& operand) const{
            return TSModulo(val*operand);
        };
        TSModulo operator/(const ll& operand) const{ //asserting MOD is prime
            return TSModulo(inverse(operand) * val);
        };

        //Binary operators on Modulo
        TSModulo operator-(const TSModulo& operand) const{
            return TSModulo(val-operand.get());
        };
        TSModulo operator+(const TSModulo& operand) const{
            return TSModulo(val+operand.get());
        };
        TSModulo operator*(const TSModulo& operand) const{
            return TSModulo(val*operand.get());
        };
        TSModulo operator/(const TSModulo& operand) const{ //asserting MOD is prime
            return TSModulo(val * inverse(operand));
        };
    };

    using Mod107 = TSModulo<1000000007LL>;

    template<ll MOD>
    ostream& operator<<(ostream& os, TSModulo<MOD> x){
        return os<<"("<<x.get()<<"%"<<MOD<<")";
    }

}
namespace mytl{
    struct Modulo{
        static ll global_mod;
    private:
        ll val;
    public:
        const ll MOD;
        Modulo(ll initMOD, ll initVal) : MOD{initMOD}, val{initVal} {
            val %= MOD;
            if(val < 0) val += MOD;
        };
        Modulo() : Modulo(global_mod, 0) {};

        static Modulo inverse(Modulo x){// asserting MOD is prime
            return power(x, x.MOD-2, x.unit());
        };
        Modulo unit() const{
            return Modulo(MOD, 1);
        }
        Modulo& operator=(const Modulo& operand){
            val = operand.val;
            return *this;
        };

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        Modulo operator-() const{
            return Modulo(MOD, -val);
        };
        Modulo operator+() const{
            return Modulo(MOD, +val);
        };

        //Binary operators on ordinary numbers
        Modulo operator-(const ll& operand) const{
            return Modulo(MOD, val-operand);
        };
        Modulo operator+(const ll& operand) const{
            return Modulo(MOD, val+operand);
        };
        Modulo operator*(const ll& operand) const{
            return Modulo(MOD, val*operand);
        };
        Modulo operator/(const ll& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(Modulo(MOD, operand)).get());
        };

        //Binary operators on Modulo
        Modulo operator-(const Modulo& operand) const{
            return Modulo(MOD, val-operand.get());
        };
        Modulo operator+(const Modulo& operand) const{
            return Modulo(MOD, val+operand.get());
        };
        Modulo operator*(const Modulo& operand) const{
            return Modulo(MOD, val*operand.get());
        };
        Modulo operator/(const Modulo& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(operand).get());
        };

    };

    ll Modulo::global_mod = 1000000007LL;

    Modulo mod107(ll x){
        return Modulo(1000000007LL, x);
    }
    ostream& operator<<(ostream& os, Modulo x){
        return os<<"("<<x.get()<<"%"<<x.MOD<<")";
    }

}
namespace mytl {

    template<class T>
    struct Resetter;

    template<class T>
    Resetter<T>* global_resetter = new Resetter<T>;

    template<class T>
    struct Resetter {

        using State = pair<counter_type, T>;

        State* state = new State{0, T()};

        Resetter(){}
        Resetter(T value){
            state = new State{0, value};
        }

        void activate(){
            global_resetter<T> = this;
        }

        void reset(T value){
            *state = State{state->first+1, value};
        }

        struct Variable{

            State state;
            State& parent = *global_resetter<T>->state;

            Variable() : state{*global_resetter<T>->state} {}
            Variable(T value) : state{global_resetter<T>->state->first, value} {}
            Variable(State st) : state{st} {}
            Variable(T value, State& parent) : state{parent->first, value} {};

            bool fresh(){
                return state.first >= parent.first;
            }

            void overwrite(){
                state = parent;
            }

            bool refresh(){
                if(!fresh()) overwrite();
            }

            T get(){
                refresh();
                return state.second;
            }

            void survive(){
                state.first = parent.first;
            }

            void operator=(T new_value){
                state.second = new_value;
                survive();
            }

        };

    };
}
namespace mytl{

    template<typename N, typename E, template<typename, typename, typename...> typename C>
    struct Container_Graph : C<N, vector<pair<E, N> > >{
        template<typename A, typename B>
        using Container = C<A,B>;
        using Edge = E;
        using Node = N;
        optional<ll> n;
        Container_Graph(ll n={}) : n{n}, Container<Node, vector<pair<Edge, Node> > >() {}

        void newEdge(Node u, Node v, Edge edge=Void()){
            (*this)[u].push_back(make_pair(edge, v));
        }
        vector<Node> getNodes(){
            vector<Node> res;
            if(n.has_value()){
                for(ll i=1; i<=n.value(); i++) res.push_back(i);
            }
            else{
                for(auto& p : *this){
                    res.push_back(p.first);
                }
            }
            return res;

        }
        vector<pair<Edge, Node> >& getEdges(Node node){
            return (*this)[node];
        }
        vector<Node > getNeighbours(Node node){
            vector<Node> res;
            for(auto& par : getEdges(node)){
                res.push_back(par.second);
            }
            return res;
        }

    };

    using NormalSimpleGraph = Container_Graph<ll, Void, AssocVector>;

    template<typename G>
    void readNeighbourList(G& g, ll indexing=1){
        for(ll i : forrange(g.n.size(), indexing)){
            for(ll neig : readValues<ll>(read<ll>())){
                g.new_edge(i, neig);
            }
        }
    }

    template<typename G>
    void readEdgeList(G& g, ll m, bool bidirectional=true){
        using Node = typename G::Node;
        using Edge = typename G::Edge;
        for(auto elem : readValues<tuple<Node, Node, Edge>, Node, Node, Edge >(m)){
            Node u, v;
            Edge edge;
            tie(u, v, edge) = elem;
            g.newEdge(u,v,edge);
            if(bidirectional) g.newEdge(v, u, edge);
        }
    }

    template<
            typename G,
            template<typename> typename QP,
            template<typename> typename P,
            typename F=void(*)(pair<typename P<G>::Info, typename G::Node>)
    >
    typename G::template Container<typename G::Node, typename P<G>::Info> queue_graph_algorithm(
            G& g,
            vector<pair<typename P<G>::Info, typename G::Node> > sources,
            F new_node_callback=[](pair<typename P<G>::Info, typename G::Node>){})
    {

        using Path = P<G>;
        using Edge = typename G::Edge;
        using Node = typename G::Node;
        using Info = typename Path::Info;
        using Option = pair<Info, Node>;
        using QueuePolicy = QP<Option>;
        using Queue = typename QueuePolicy::Queue;

        Queue q;
        for(auto source : sources) QueuePolicy::push(q, source);
        typename G::template Container<Node, Info> d;
        while(!q.empty()){
            auto akt = QueuePolicy::consume(q);
            Node who = akt.second;
            Info info = akt.first;

            if(has_key(d, who)) continue;

            d[who] = info;

            new_node_callback(pair<Info, Node>(info, who));
            for(auto par : g.getEdges(who)) if(!has_key(d, par.second)){
                    QueuePolicy::push(q, {Path::append({info, who}, par.first, par.second), par.second});
                }
        }
        return d;
    }

/*template<template<typename> typename QP, template<typename> typename P>
struct AlgoComposer{
    template<typename G>
    struct A{
        using Path = P<G>;
        using Edge = typename G::Edge;
        using Node = typename G::Node;
        using Info = typename Path::Info;
        using Option = pair<Info, Node>;
        using QueuePolicy = QP<Option>;
        using Queue = typename QueuePolicy::Queue;

        static Option consume(Queue& q){
            return QueuePolicy::consume(q);
        }
        static void push(Queue& q, Option new_option){
            return QueuePolicy::push(q, new_option);
        }
        static Info append(pair<Info, Node> from , Edge e, Node to){
            return Path::append(from, e, to);
        }
    };
};
*/

    template<typename T>
    struct Priority{
        using Queue = priority_queue<T, vector<T>, greater<T> >;
        static T consume(Queue& q){
            auto res = q.top();
            q.pop();
            return res;
        }
        static void push(Queue& q, T new_option){
            q.push(new_option);
        }
    };

    template<typename T>
    struct FIFO{
        using Queue = queue<T>;
        static T consume(Queue& q){
            auto res = q.front();
            q.pop();
            return res;
        }
        static void push(Queue& q, T new_option){
            q.push(new_option);
        }
    };

    template<typename T>
    struct FILO{
        using Queue = stack<T>;
        static T consume(Queue& q){
            auto res = q.top();
            q.pop();
            return res;
        }
        static void push(Queue& q, T new_option){
            q.pop();
        }
    };

    template<typename G>
    struct JustLength{
        using Info = typename G::Edge;
        static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
            return from.first + e;
        }
    };

    template<typename G>
    struct SimpleJustLength{
        using Info = ll;
        static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
            return from.first + 1;
        }
    };

    template<typename G>
    struct LengthAndLastNode{
        using Info = pair<ll, typename G::Node>;
        static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
            return {from.first + e, from.second};
        }
    };

    template<typename G>
    struct SimpleLengthAndLastNode{
        using Info = pair<typename G::Edge, typename G::Node>;
        static Info append(pair<Info, typename G::Node> from, typename G::Edge e, typename G::Node n){
            return {from.first + 1, from.second};
        }
    };

/*
template<typename G>
struct Custom{
    using Edge = typename G::Edge;
    using Node = typename G::Node;

    using Info = _;
    using Option = pair<Info, Edge>;
    using Queue = _;

    static Option consume(Queue &q){
        _
        return _;
    }

    static void push(Queue &q, Option new_option){
        _
    }

    static Info append(Option from, Edge e, Node to){
        return _
    }

};
*/
}
namespace mytl{

    struct Point{
        ll x, y;

        Point(ll x, ll y) : x{x}, y{y} {};
        Point(pair<ll,ll> initPair) : x{initPair.first}, y{initPair.second} {};

        pair<ll,ll> getPair(){//not introducing type cast operator for safety
            return {x,y};
        }

        //Unary operators
        Point operator-() const{
            return {-x, -y};
        }
        Point operator+() const{
            return {x,y};
        }

        static ll sgn(ll x){
            return (x > 0) - (x < 0);
        }

        //Binary operators on ordinary numbers
        Point operator*(const ll& operand) const{
            return {x*operand, y*operand};
        }

        //Binary operators on Point itself
        Point operator+(const Point& operand) const{
            return {x+operand.x, y+operand.y};
        }
        Point operator-(const Point& operand) const{
            return {x-operand.x, y-operand.y};
        }

        ll operator*(const Point& operand){ //vectorial product
            return x*operand.y - y*operand.x;
        }

        ll direction(const Point& a, const Point& b) const{
            return sgn((a - *this) * (b - *this));
        };
    };

    ll distance_squared(const Point& a, const Point& b){
        return (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y);
    }

    double distance(const Point& a, const Point& b){
        return sqrt(distance_squared(a, b));
    }

    ll cartesian_distance(const Point& a, const Point& b){
        return abs(a.x - b.x) + abs(a.y - b.y);
    }

    typedef vector<Point> Poly;

    bool inside(const Poly& poly, const Point& point, bool strict){ //assuming Poly is weakly convex
        ll prevdir = -2;
        for(ll i=0; i<poly.size(); i++){
            ll nexdindex = (i+1)%poly.size();
            ll dir = poly[i].direction(poly[nexdindex], point);
            if(dir == 0){
                if(strict) return false;
            }
            else{
                if(dir != prevdir && prevdir != -2) return false;
                prevdir = dir;
            }

        }
        return true;
    }

}
namespace mytl{
    template<class Op>
    struct Node : Op::Range{
        using Range = typename Op::Range;
        using T = typename Op::T;
        using Change = typename Op::Change;
        using Range::singleton;
        using Range::inside;
        using Range::intersect;
        using Range::leftHalf;
        using Range::rightHalf;

        Node *left_child=NULL, *right_child=NULL;

        T partial;
        Change pending = Op::identity();

        Node(Range range) : Range(range), partial{Op::initial(range)} {};

        T query(Range range, Change change){
            return query_(range, change).first;
        }

        void add(Change change){
            pending = Op::push(pending, change);
        }

        void prepare(){
            if(!singleton()){
                if(left_child == NULL) left_child = (new Node(leftHalf()));
                if(right_child == NULL) right_child = (new Node(rightHalf()));
                left_child->add(pending);
                right_child->add(pending);
            }
            partial = Op::apply(*this, partial, pending);
            pending = Op::identity();
        }

        pair<T,T> query_(Range range, Change change){
            //cout<<range<<" "<<*this<<endl;
            prepare();
            if(inside(range)){
                add(change);
                prepare();
                return {partial, Op::zero()};
            }
            if(!intersect(range)){
                //cout<<"n"<<range<<" "<<*this<<endl;
                return {Op::zero(), partial};
            }

            auto from_left = left_child->query_(range, change);
            auto from_right = right_child->query_(range, change);
            //cout<<from_right.first<<endl;
            auto needed = Op::reduce(from_left.first, from_right.first), rest = Op::reduce(from_left.second, from_right.second);
            partial = Op::reduce(needed, rest);
            return {needed, rest};
        }

        T build_from(const function<T(ll)>& getter){
            prepare();
            pending = Op::identity();
            if(singleton()) partial = getter(this->first);
            else partial = Op::reduce(left_child->build_from(getter), right_child->build_from(getter));
            return partial;
        }

    };

    struct Range1D : PairOf<ll>{
        using PairOf<ll>::pair;

        ll span() const {
            return second-first+1;
        }
        bool singleton() const {
            return span() == 1;
        }
        Range1D leftHalf() const {
            return Range1D(first, (first+second)/2);
        }
        Range1D rightHalf() const {
            return Range1D((first + second)/2 + 1, second);
        }
        bool inside(const Range1D& other) const {
            return other.first <= first && second <= other.second;
        }
        bool intersect(const Range1D& other) const {

            return other.inside(*this)
                   ||(other.first <= first && first <= other.second)
                   ||(other.first <= second && second <= other.second);
        }
    };

}

namespace mytl{
    template<typename T_>
    struct Add_Sum{
        using Range = Range1D;
        using T = T_;
        using Change = T_;

        static Change identity(){
            return 0;
        }

        static T zero(){
            return 0;
        }

        static T initial(Range r){
            return zero();
        }

        static T reduce(T a, T b){
            return a + b;
        }

        static T apply(Range r, T a, Change c){
            return a + r.span()*c;
        }

        static Change push(Change a, Change b){
            return a + b;
        }
    };

    template<typename T_>
    struct Multiply_Sum{
        using Range = Range1D;
        using T = T_;
        using Change = T_;

        static Change identity(){
            return 1;
        }

        static T zero(){
            return 0;
        }

        static T initial(Range r){
            return r.span()*1;
        }

        static T reduce(T a, T b){
            return a + b;
        }

        static T apply(Range r, T a, Change c){
            return a*c;
        }

        static Change push(Change a, Change b){
            return a*b;
        }
    };

}

namespace mytl{
/*
struct Custom_Op{
    using Range = _;
    using T = _;
    using Change = _;

    static Change identity(){
        return _;
    }

    static T zero(){
        return _;
    }

    static T initial(Range r){
        return _;
    }

    static T reduce(T a, T b){
        return _;
    }

    static T apply(Range r, T a, Change c){
        return _;
    }

    static Change push(Change a, Change b){
        return _;
    }

};
*/

}
namespace mytl{

    template <template<typename, typename, typename...> typename C, typename Arg, typename R>
    function<R (Arg)> memoize(R (*fn)(Arg)) {
        C<Arg, optional<R> > table;
        return [fn, table](Arg arg) mutable -> R {
            optional<R>& res = table[arg];
            if(!res.has_value()){
                res = fn(arg);
            }
            return res.value();
        };
    }

}
//ENDCOPY

using G = mytl::Container_Graph<ll, Void, mytl::AssocVector>;

void processs(){
    ll n;
    cin>>n;
    G g(n);
    mytl::readEdgeList(g, n-1);

    //cout<<"hh";
    auto enyem_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> enyem(enyem_.begin(), enyem_.end());
    auto ove_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> ove(ove_.begin(), ove_.end());

    //cout<<enyem<<" "<<ove<<endl;
    auto ask = [&](ll& ide, char tipus, ll ki) -> bool{
        cout<<tipus<<" "<<ki<<endl;
        ll got;
        cin>>got;
        if(tipus == 'A' && mytl::has_key(ove, got)){
            cout<<"C "<<ki<<endl;
            return true;
        }
        if(tipus == 'B' && mytl::has_key(enyem, got)){
            cout<<"C "<<got<<endl;
            return true;
        }
        ide = got;
        return false;

    };

    ll one_piece;
    if(ask(one_piece, 'B', *ove.begin())) return;
    vector<pair<pair<Void,ll>, ll> > sour{{{Void(),-1}, *enyem.begin()}};
    // cout<<sour<<endl;
    auto tb = mytl::queue_graph_algorithm<G, mytl::FILO,mytl::SimpleLengthAndLastNode>(g,sour);

    while(!mytl::has_key(enyem, one_piece)){
        one_piece = tb[one_piece].second;
    }

    ll dc;
    if(ask(dc, 'A', one_piece)) return;
    else{
        cout<<"C -1"<<endl;
    }

}

MAIN main(){
    ll T;
    cin>>T;
    mytl::repeat(T, [&](){
        processs();
    }) ;
}


#include<bits/stdc++.h>
using namespace std;

using u_counter_type = unsigned int;
using need_int = int;
using counter_type = int;
using MAIN = int;
#define int DontUseIntÉ
using ll = long long;

template<typename T>
using PairOf = pair<T,T>;

using Void = tuple<>;

struct BasicInitialization{
    BasicInitialization(){
        ios_base::sync_with_stdio(false);
    }
};
BasicInitialization __basic_initialization__;
namespace mytl{

template<typename T>
struct Lazy : optional<T>{

    function<T()> f;

    Lazy(function<T()> f) : f{f}, optional<T>() {};

    T& value(){
        if(!this->has_value()){
            optional<T>::operator=(f());
        }
        return optional<T>::value();
    }

};

#define LAZY(val, tipe) mytl::Lazy<tipe>([&](){return (val);})

}
namespace mytl{

template<typename T>
T discrete_binary_search(function<bool(T)> f, T l, T r){
    if(!f(l)) return l;
    while(l < r){
        T pivot = (l+r)/2;
        if(!f(pivot)) r = pivot-1;
        else if(!f(pivot+1)) l = r = pivot;
        else l = pivot+1;
    }
    return l;
}

template<typename T>
T continuous_binary_search(function<bool(T)> f, T l, T r, need_int iterations){
    mytl::repeat(iterations,[&](){
        T pivot = (l+r)/2;
        if(f(pivot)) l = pivot;
        else r = pivot;
    });
    return l;
}
}

namespace std{

template<typename T>
istream& operator>>(istream& is, optional<T>& x){
    if(!x.has_value()){
        T x_;
        is>>x_;
        x = x_;
    }
    return is;
}

istream& operator>>(istream& is, Void& x){
    return is;
}

template<typename P, typename Q>
istream& operator>>(istream& is, pair<P,Q> x){
    return is>>x.first>>x.second;
}

template<typename P, typename Q>
ostream& operator<<(ostream& os, const pair<P,Q>& x){
    os<<"("<<x.first<<", "<<x.second<<")";
    return os;
}

template<typename T, template<typename, typename...> typename Container>
ostream& operator<<(ostream& os, const Container<T>& x){
    os<<"{";
    bool first = true;
    for(const auto& elem : x){
        if(!first) os<<", ";
        os<<elem;
        first = false;
    }
    os<<"}";
    return os;
}

}

namespace mytl{

template<typename T, typename P=T>
T read(istream& is=cin){
    P a;
    is>>a;
    return T(a);
}

template<typename T, typename P, typename Q>
T read(istream& is=cin){
    P a;
    Q b;
    is>>a>>b;
    return T(a,b);
}

template<typename T, typename P, typename Q, typename R>
T read(istream& is=cin){
    P a;
    Q b;
    R c;
    is>>a>>b>>c;
    return T(a,b,c);
}

template<typename T, typename... Q, typename Container=vector<T>>
vector<T> readValues(ll n, istream& is=cin){
    vector<T> res;
    repeat(n, [&res](){
        res.push_back(read<T,Q...>());
    });
    return Container(res.begin(), res.end());
}

}

namespace mytl{

template<typename T>
void print(const T& x, ostream& os=cout){
    os<<x;
}

}
namespace mytl{
    template<ll MOD>
    struct TSModulo{
    private:
        ll val;

    public:
        static TSModulo inverse(TSModulo x){// asserting MOD is prime
            return power(x, MOD-2);
        };
        TSModulo(ll initVal) : val{(MOD + initVal%MOD)%MOD} {};
        TSModulo() : TSModulo(0) {}
        TSModulo& operator=(const TSModulo&) = default;

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        TSModulo operator-() const{
            return TSModulo(-val);
        };
        TSModulo operator+() const{
            return TSModulo(+val);
        };

        //Binary operators on ordinary numbers
        TSModulo operator-(const ll& operand) const{
            return TSModulo(val-operand);
        };
        TSModulo operator+(const ll& operand) const{
            return TSModulo(val+operand);
        };
        TSModulo operator*(const ll& operand) const{
            return TSModulo(val*operand);
        };
        TSModulo operator/(const ll& operand) const{ //asserting MOD is prime
            return TSModulo(inverse(operand) * val);
        };

        //Binary operators on Modulo
        TSModulo operator-(const TSModulo& operand) const{
            return TSModulo(val-operand.get());
        };
        TSModulo operator+(const TSModulo& operand) const{
            return TSModulo(val+operand.get());
        };
        TSModulo operator*(const TSModulo& operand) const{
            return TSModulo(val*operand.get());
        };
        TSModulo operator/(const TSModulo& operand) const{ //asserting MOD is prime
            return TSModulo(val * inverse(operand));
        };
    };

    using Mod107 = TSModulo<1000000007LL>;

    template<ll MOD>
    ostream& operator<<(ostream& os, TSModulo<MOD> x){
        return os<<"("<<x.get()<<"%"<<MOD<<")";
    }

}
namespace mytl{

template<typename T>
struct LazyVector : vector<T>{
    typename vector<T>::reference operator[](counter_type i){
        if(i >= this->size()) this->resize(i+1);
        return vector<T>::operator[](i);
    }
};

template<typename K, typename T>
struct AssocVector : LazyVector<T>{
    LazyVector<bool> exists;
    typename vector<T>::reference operator[](counter_type i){
        exists[i] = true;
        return LazyVector<T>::operator[](i);
    }
    typename vector<T>::iterator find(counter_type i){
        if(!exists[i]) return this->end();
        else return this->begin() + i;
    }
};

template<template<typename, typename, typename...> typename Container, typename Key, typename Value>
bool has_key(Container<Key, Value>& container, Key key){
    return container.find(key) != container.end();
}

}
namespace mytl{
    struct Modulo{
        static ll global_mod;
    private:
        ll val;
    public:
        const ll MOD;
        Modulo(ll initMOD, ll initVal) : MOD{initMOD}, val{initVal} {
            val %= MOD;
            if(val < 0) val += MOD;
        };
        Modulo() : Modulo(global_mod, 0) {};

        static Modulo inverse(Modulo x){// asserting MOD is prime
            return power(x, x.MOD-2, x.unit());
        };
        Modulo unit() const{
            return Modulo(MOD, 1);
        }
        Modulo& operator=(const Modulo& operand){
            val = operand.val;
            return *this;
        };

        ll get() const{ // no type cast operator to prevent accidentally turning into ordinary number
            return val;
        }

        //Unary operators
        Modulo operator-() const{
            return Modulo(MOD, -val);
        };
        Modulo operator+() const{
            return Modulo(MOD, +val);
        };

        //Binary operators on ordinary numbers
        Modulo operator-(const ll& operand) const{
            return Modulo(MOD, val-operand);
        };
        Modulo operator+(const ll& operand) const{
            return Modulo(MOD, val+operand);
        };
        Modulo operator*(const ll& operand) const{
            return Modulo(MOD, val*operand);
        };
        Modulo operator/(const ll& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(Modulo(MOD, operand)).get());
        };

        //Binary operators on Modulo
        Modulo operator-(const Modulo& operand) const{
            return Modulo(MOD, val-operand.get());
        };
        Modulo operator+(const Modulo& operand) const{
            return Modulo(MOD, val+operand.get());
        };
        Modulo operator*(const Modulo& operand) const{
            return Modulo(MOD, val*operand.get());
        };
        Modulo operator/(const Modulo& operand) const{ //asserting MOD is prime
            return Modulo(MOD, val * inverse(operand).get());
        };

    };

    ll Modulo::global_mod = 1000000007LL;

    Modulo mod107(ll x){
        return Modulo(1000000007LL, x);
    }
    ostream& operator<<(ostream& os, Modulo x){
        return os<<"("<<x.get()<<"%"<<x.MOD<<")";
    }

}
namespace mytl {

template<class T>
struct Resetter;

template<class T>
Resetter<T>* global_resetter = new Resetter<T>;

template<class T>
struct Resetter {

    using State = pair<counter_type, T>;

    State* state = new State{0, T()};

    Resetter(){}
    Resetter(T value){
        state = new State{0, value};
    }

    void activate(){
        global_resetter<T> = this;
    }

    void reset(T value){
        *state = State{state->first+1, value};
    }

    struct Variable{

        State state;
        State& parent = *global_resetter<T>->state;

        Variable() : state{*global_resetter<T>->state} {}
        Variable(T value) : state{global_resetter<T>->state->first, value} {}
        Variable(State st) : state{st} {}
        Variable(T value, State& parent) : state{parent->first, value} {};

        bool fresh(){
            return state.first >= parent.first;
        }

        void overwrite(){
            state = parent;
        }

        bool refresh(){
            if(!fresh()) overwrite();
        }

        T get(){
            refresh();
            return state.second;
        }

        void survive(){
            state.first = parent.first;
        }

        void operator=(T new_value){
            state.second = new_value;
            survive();
        }

    };

};
}
namespace mytl{

template<typename N, typename E, template<typename, typename, typename...> typename C>
struct Container_Graph{
    template<typename A, typename B>
    using Container = C<A,B>;
    using Edge = E;
    using Node = N;
    struct Arm{
        Edge edge;
        Node node;
    };

    Container<Node,  vector<Arm> > container;

    optional<ll> n;
    Container_Graph(ll n={}) : n{n}, container() {}

    void newEdge(Node u, Node v, Edge edge=Void()){
        container[u].push_back({edge, v});
    }
    vector<Node> getNodes(){
        vector<Node> res;
        if(n.has_value()){
            for(ll i=1; i<=n.value(); i++) res.push_back(i);
        }
        else{
            for(auto& p : container){
                res.push_back(p.first);
            }
        }
        return res;

    }
    vector<Arm >& getEdges(Node node){
        return container[node];
    }
    vector<Node > getNeighbours(Node node){
        vector<Node> res;
        for(auto& arm : getEdges(node)){
            res.push_back(arm.node);
        }
        return res;
    }

};

using NormalSimpleGraph = Container_Graph<ll, Void, AssocVector>;

template<typename G>
void readNeighbourList(G& g, ll indexing=1){
    for(ll i : forrange(g.n.size(), indexing)){
        for(ll neig : readValues<ll>(read<ll>())){
            g.new_edge(i, neig);
        }
    }
}

template<typename G>
void readEdgeList(G& g, ll m, bool bidirectional=true){
    using Node = typename G::Node;
    using Edge = typename G::Edge;
    for(auto elem : readValues<tuple<Node, Node, Edge>, Node, Node, Edge >(m)){
        Node u, v;
        Edge edge;
        tie(u, v, edge) = elem;
        g.newEdge(u,v,edge);
        if(bidirectional) g.newEdge(v, u, edge);
    }
}

template<typename G, template<typename> typename Path>
struct Reaching{
    typename Path<G>::Info info;
    typename G::Node node;
    bool operator<(const Reaching& other) const {
        return info > other.info;
    }
};

template<
    typename G,
    template<typename> typename QP,
    template<typename> typename P,
    typename F=void(*)(typename P<G>::Info, typename G::Node)
>
typename G::template Container<typename G::Node, typename P<G>::Info> queue_graph_algorithm(
    G& g,
    vector<Reaching<G,P> > sources,
    F new_node_callback=[](typename P<G>::Info, typename G::Node){})
{

    using Path = P<G>;
    using Edge = typename G::Edge;
    using Node = typename G::Node;
    using Info = typename Path::Info;
    //using Option = pair<Info, Node>;
    using R = Reaching<G,P>;
    using QueuePolicy = QP<R>;
    using Queue = typename QueuePolicy::Queue;

    Queue q;
    for(R source : sources) QueuePolicy::push(q, source);
    typename G::template Container<Node, Info> d;
    while(!q.empty()){
        R akt = QueuePolicy::consume(q);

        if(has_key(d, akt.node)) continue;

        d[akt.node] = akt.info;

        new_node_callback(akt.info, akt.node);
        for(auto arm : g.getEdges(akt.node)) if(!has_key(d, arm.node)){
            QueuePolicy::push(q, {Path::append(akt.info, akt.node, arm.edge, arm.node), arm.node});
        }
    }
    return d;
}

template<
        typename G,
        template<typename> typename QP,
        template<typename> typename P,
        typename F=void(*)(typename P<G>::Info, typename G::Node)
>
typename G::template Container<typename G::Node, typename P<G>::Info> queue_graph_algorithm_from_single_source(
        G& g,
        typename P<G>::Info info,
        typename G::Node node,
        F new_node_callback=[](typename P<G>::Info, typename G::Node){})
{
    return queue_graph_algorithm<G,QP,P,F>(g, {{info,node}},new_node_callback);
}

template<typename T>
struct Priority{
    using Queue = priority_queue<T>;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FIFO{
    using Queue = queue<T>;
    static T consume(Queue& q){
        auto res = q.front();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.push(new_option);
    }
};

template<typename T>
struct FILO{
    using Queue = stack<T>;
    static T consume(Queue& q){
        auto res = q.top();
        q.pop();
        return res;
    }
    static void push(Queue& q, T new_option){
        q.pop();
    }
};

template<typename G>
struct JustLength{
    using Info = typename G::Edge;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return old_info + e;
    }
};

template<typename G>
struct SimpleJustLength{
    using Info = ll;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return old_info + 1;
    }
};

template<typename G>
struct LengthAndLastNode{
    using Info = pair<ll, typename G::Node>;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return {old_info + e, old_node};
    }
};

template<typename G>
struct SimpleLengthAndLastNode{
    using Info = pair<typename G::Edge, typename G::Node>;
    static Info append(Info old_info, typename G::Node old_node, typename G::Edge e, typename G::Node n){
        return {old_info + 1, old_node};
    }
};

}
namespace mytl{

template<typename T, typename R, typename F=function<R(T)> >
vector<R> fmap(F f, const vector<T>& t){
    vector<R> res;
    for(auto elem : t) res.push_back(f(elem));
    return res;
}

template<typename T>
vector<T> forrange(T n, T from){
    vector<T> res(n);
    iota(res.begin(), res.end(), from);
    return res;
}

template<typename F>
void repeat(need_int n, const F& callback){
    for(need_int _ : forrange(n,0)) callback();
}

template<typename T, template<typename, typename...> typename Container>
vector<PairOf<T&> > adjecent_pairs(Container<T>& c){
    vector<PairOf<T&> > res;
    optional<T*> prev_elem;
    for(auto& elem : c){
        if(prev_elem.has_value()){
            res.push_back({*prev_elem.value(), elem});
        }
        prev_elem = &elem;
    }
    return res;
}
#define WATCH(x) cout << (#x) << " is " << (x) << endl
}
namespace mytl{

struct Point{
    ll x, y;

    Point(ll x, ll y) : x{x}, y{y} {};
    Point(pair<ll,ll> initPair) : x{initPair.first}, y{initPair.second} {};

    pair<ll,ll> getPair(){//not introducing type cast operator for safety
        return {x,y};
    }

    //Unary operators
    Point operator-() const{
        return {-x, -y};
    }
    Point operator+() const{
        return {x,y};
    }

    static ll sgn(ll x){
        return (x > 0) - (x < 0);
    }

    //Binary operators on ordinary numbers
    Point operator*(const ll& operand) const{
        return {x*operand, y*operand};
    }

    //Binary operators on Point itself
    Point operator+(const Point& operand) const{
        return {x+operand.x, y+operand.y};
    }
    Point operator-(const Point& operand) const{
        return {x-operand.x, y-operand.y};
    }

    ll operator*(const Point& operand){ //vectorial product
        return x*operand.y - y*operand.x;
    }

    ll direction(const Point& a, const Point& b) const{
        return sgn((a - *this) * (b - *this));
    };
};

ll distance_squared(const Point& a, const Point& b){
    return (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y);
}

double distance(const Point& a, const Point& b){
    return sqrt(distance_squared(a, b));
}

ll cartesian_distance(const Point& a, const Point& b){
    return abs(a.x - b.x) + abs(a.y - b.y);
}

typedef vector<Point> Poly;

bool inside(const Poly& poly, const Point& point, bool strict){ //assuming Poly is weakly convex
    ll prevdir = -2;
    for(ll i=0; i<poly.size(); i++){
        ll nexdindex = (i+1)%poly.size();
        ll dir = poly[i].direction(poly[nexdindex], point);
        if(dir == 0){
            if(strict) return false;
        }
        else{
            if(dir != prevdir && prevdir != -2) return false;
            prevdir = dir;
        }

    }
    return true;
}

}
namespace mytl{
template<class Op>
struct Node : Op::Range{
    using Range = typename Op::Range;
    using T = typename Op::T;
    using Change = typename Op::Change;
    using Range::singleton;
    using Range::inside;
    using Range::intersect;
    using Range::leftHalf;
    using Range::rightHalf;

    Node *left_child=NULL, *right_child=NULL;

    T partial;
    Change pending = Op::identity();

    Node(Range range) : Range(range), partial{Op::initial(range)} {};

    T query(Range range, Change change){
        return query_(range, change).first;
    }

    void add(Change change){
        pending = Op::push(pending, change);
    }

    void prepare(){
        if(!singleton()){
            if(left_child == NULL) left_child = (new Node(leftHalf()));
            if(right_child == NULL) right_child = (new Node(rightHalf()));
            left_child->add(pending);
            right_child->add(pending);
        }
        partial = Op::apply(*this, partial, pending);
        pending = Op::identity();
    }

    pair<T,T> query_(Range range, Change change){
        //cout<<range<<" "<<*this<<endl;
        prepare();
        if(inside(range)){
            add(change);
            prepare();
            return {partial, Op::zero()};
        }
        if(!intersect(range)){
            //cout<<"n"<<range<<" "<<*this<<endl;
            return {Op::zero(), partial};
        }

        auto from_left = left_child->query_(range, change);
        auto from_right = right_child->query_(range, change);
        //cout<<from_right.first<<endl;
        auto needed = Op::reduce(from_left.first, from_right.first), rest = Op::reduce(from_left.second, from_right.second);
        partial = Op::reduce(needed, rest);
        return {needed, rest};
    }

    T build_from(const function<T(ll)>& getter){
        prepare();
        pending = Op::identity();
        if(singleton()) partial = getter(this->l);
        else partial = Op::reduce(left_child->build_from(getter), right_child->build_from(getter));
        return partial;
    }

};

struct Range1D{

    ll l, r;

    Range1D(ll l, ll r): l{l}, r{r} {}

    ll span() const {
        return r-l+1;
    }
    bool singleton() const {
        return span() == 1;
    }
    Range1D leftHalf() const {
        return Range1D(l, (l+r)/2);
    }
    Range1D rightHalf() const {
        return Range1D((l + r)/2 + 1, r);
    }
    bool inside(const Range1D& other) const {
        return other.l <= l && r <= other.r;
    }
    bool intersect(const Range1D& other) const {

        return other.inside(*this)
             ||(other.l <= l && l <= other.r)
             ||(other.l <= r && r <= other.r);
    }
};

}

namespace mytl{
template<typename T_>
struct Add_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 0;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return zero();
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a + r.span()*c;
    }

    static Change push(Change a, Change b){
        return a + b;
    }
};

template<typename T_>
struct Multiply_Sum{
    using Range = Range1D;
    using T = T_;
    using Change = T_;

    static Change identity(){
        return 1;
    }

    static T zero(){
        return 0;
    }

    static T initial(Range r){
        return r.span()*1;
    }

    static T reduce(T a, T b){
        return a + b;
    }

    static T apply(Range r, T a, Change c){
        return a*c;
    }

    static Change push(Change a, Change b){
        return a*b;
    }
};

}

namespace mytl{
/*
struct Custom_Op{
    using Range = _;
    using T = _;
    using Change = _;

    static Change identity(){
        return _;
    }

    static T zero(){
        return _;
    }

    static T initial(Range r){
        return _;
    }

    static T reduce(T a, T b){
        return _;
    }

    static T apply(Range r, T a, Change c){
        return _;
    }

    static Change push(Change a, Change b){
        return _;
    }

};
*/

}
namespace mytl{
template<typename T>
T power(T base, ll exponential, T unit=1){
    T res = unit;
    while(exponential > 0){
        if(exponential%2 == 1) res = res * base;
        base = base * base;
        exponential = exponential / 2;
    }
    return res;
}
}
namespace mytl{

template<typename T, T(*f)(T,T)>
struct Tracker : optional<T>{

    Tracker() : optional<T>() {};

    void update(T val){
        if(this->has_value()){
            optional<T>::operator=(f(this->value(), val));
        }
        else{
            optional<T>::operator=(val);
        }
    }
};

template<typename T>
T min(T a, T b){return std::min(a,b);}
template<typename T>
T max(T a, T b){return std::max(a,b);}
template<typename T>
T __gcd(T a, T b){return std::__gcd(a,b);}

}
namespace mytl{

template <template<typename, typename, typename...> typename C, typename Arg, typename R>
function<R (Arg)> memoize(R (*fn)(Arg)) {
    C<Arg, optional<R> > table;
    return [fn, table](Arg arg) mutable -> R {
        optional<R>& res = table[arg];
        if(!res.has_value()){
            res = fn(arg);
        }
        return res.value();
    };
}

}

using G = mytl::Container_Graph<ll, Void, mytl::AssocVector>;

void processs(){
    ll n;
    cin>>n;
    G g(n);
    mytl::readEdgeList(g, n-1);

        //cout<<"hh";
    auto enyem_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> enyem(enyem_.begin(), enyem_.end());
    auto ove_ = mytl::readValues<ll>(mytl::read<ll>());
    set<ll> ove(ove_.begin(), ove_.end());

    //cout<<enyem<<" "<<ove<<endl;
    auto ask = [&](ll& ide, char tipus, ll ki) -> bool{
        cout<<tipus<<" "<<ki<<endl;
        ll got;
        cin>>got;
        if(tipus == 'A' && mytl::has_key(ove, got)){
            cout<<"C "<<ki<<endl;
            return true;
        }
        if(tipus == 'B' && mytl::has_key(enyem, got)){
            cout<<"C "<<got<<endl;
            return true;
        }
        ide = got;
        return false;

    };

    ll one_piece;
    if(ask(one_piece, 'B', *ove.begin())) return;
     vector<pair<pair<ll,ll>, ll> > sour{{{0,-1}, *enyem.begin()}};
    // cout<<sour<<endl;
   auto tb = mytl::queue_graph_algorithm<G, mytl::AlgoComposer<mytl::FILO,mytl::SimpleLengthAndLastNode>::A >(g,sour);

    while(!mytl::has_key(enyem, one_piece)){
        one_piece = tb[one_piece].second;
    }

    ll dc;
    if(ask(dc, 'A', one_piece)) return;
    else{
        cout<<"C -1"<<endl;
    }

}

MAIN main(){
    ll T;
    cin>>T;
    mytl::repeat(T, [&](){
        processs();
    }) ;
}