Compilare: user.cpp: In function ‘int main()’: user.cpp:54:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i<P.size() && j < M.size()) ^ user.cpp:54:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i<P.size() && j < M.size()) ^ user.cpp:62:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (;i<P.size();i++) ^ user.cpp:64:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (;j<M.size();j++) ^