?- consult('crypto.pro').
%  ../gv.pro compiled 0.01 sec, 2,696 bytes
%  ../combosets.pro compiled 0.00 sec, 7,560 bytes
% crypto.pro compiled 0.01 sec, 18,848 bytes

Yes
?- crypto(6,2,4,9,14,11,K).

K = ex(ex(9, +, 14), -, ex(4, +, ex(6, +, 2)))

Yes
?- crypto(1,1,1,3,6,8,K).

K = ex(ex(1, -, ex(1, +, 1)), +, ex(3, +, 6))

Yes
?- crypto(1,1,1,3,6,14,K).

K = ex(ex(ex(1, *, 3), -, 1), *, ex(1, +, 6))

Yes
?- crypto(1,1,1,3,6,15,K).

K = ex(ex(3, *, 6), -, ex(1, +, ex(1, +, 1)))

Yes
?- halt.