Compilare: user.cpp: In function ‘bool solve(int)’: user.cpp:39:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = how_many; i < a.size(); ++i) { ^ user.cpp:55:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = how_many; i < b.size(); ++i) { ^ user.cpp:25:20: warning: variable ‘hash2’ set but not used [-Wunused-but-set-variable] int hash1 = 0, hash2 = 0, P1 = 1, P2 = 1; ^ user.cpp:25:39: warning: unused variable ‘P2’ [-Wunused-variable] int hash1 = 0, hash2 = 0, P1 = 1, P2 = 1; ^