Kirill live connect undirected graph n vertex m edge vertex 1 one fine evening gather f friend ith friend live vertex h_i so friend vertex 1 ith friend home vertex h_ithe evening end time leave it turn k k le 6 friend car walk give ride one friend car ride number friend car ride drive short path housefor example graph friend vertex h_i5 ride friend follow set vertex 2 3 2 4 2 3 4 can not ride friend vertex 6 set 3 4 the vertex friend car live highlight green car red Kirill want friend possible walk help find minimum possible number