Compilare: user.cpp: In function ‘void debug()’: user.cpp:34:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1 ; i <= n ; ++i) {out<<"\nNIVELUL "<<i<<" : \n"; ^ user.cpp:36:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < a[i].size(); ++j) ^