Compilare: user.cpp: In function ‘int main()’: user.cpp:55:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<X.size()-1;i++) { ^ user.cpp:56:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<M.size();j++) { ^ user.cpp:66:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<X.size()-1;i++) ^