Compilare: user.cpp: In function ‘void solve(int)’: user.cpp:39:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < sol.size(); i++ ) ^ user.cpp:45:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < sol.size(); i++ ) ^ user.cpp: In function ‘int main()’: user.cpp:55:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < sol.size(); i++ ) ^