Compilare: user.cpp: In function ‘int main()’: user.cpp:46:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<sol.size() - 1; i++){ ~^~~~~~~~~~~~~~~ user.cpp:54:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (sol.size() != n) return cout << 0, 0; ~~~~~~~~~~~^~~~