Compilare: user.cpp: In function ‘void solve()’: user.cpp:69:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:114:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(it=0; it<solution.size()-1; it++) ^