Compilare: user.cpp: In function ‘bool verif(std::string)’: user.cpp:15:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i<s.size(); ++i) ^ user.cpp: In function ‘void solve(std::string)’: user.cpp:38:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i<s.size(); ++i) ^ user.cpp:47:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i<perechi.size(); ++i) ^ user.cpp:48:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1 <= perechi.size()/2) ^