Compilare: user.cpp: In function ‘int main()’: user.cpp:15:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < s.size(); ++i) ^ user.cpp:19:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < j && j < s.size()){ ^ user.cpp:33:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < sol.size() ; ++i) ^