Among the four number cards 3, 1, 9, and 7, find the two cards with the greatest difference and add them together.
[OP_LIST_SOL] 3 1 9 7 [OP_LIST_EOL] 1 [OP_LIST_MAX] 1 [OP_LIST_MIN] [OP_ADD}
var_a = 3
var_b = 1
var_c = 9
var_d = 7
list_a= []
if "/" in str(var_d):
    var_d = eval(str(var_d))
list_a.append(var_d)
if "/" in str(var_c):
    var_c = eval(str(var_c))
list_a.append(var_c)
if "/" in str(var_b):
    var_b = eval(str(var_b))
list_a.append(var_b)
if "/" in str(var_a):
    var_a = eval(str(var_a))
list_a.append(var_a)
list_a.reverse()
var_e = 1
list_b=list_a.copy()
list_b.sort()
var_f = list_b[-var_e]
var_g = 1
list_c=list_a.copy()
list_c.sort()
var_h = list_c[var_g-1]
var_i = '[OP_ADD}'
print(var_i)