Compilare: user.cpp: In function ‘int main()’: user.cpp:21:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.length() ; i++) ^ user.cpp:23:65: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (!st.empty() && (s[i]>st.top()) && (m - st.size() < n - i)) ^ user.cpp:27:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (st.size() != m) ^