Compilare: user.cpp: In function ‘int main()’: user.cpp:27:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = j ; i < s.size(); i++) ^ user.cpp:74:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = k; i <= s.size(); i++) ^ user.cpp:76:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == s.size()) ^