Compilare: user.cpp: In function ‘void sort_top(int)’: user.cpp:11:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[x].size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:39:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<Q[V[k]].size();++i) ^ user.cpp:46:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<G[V[j]].size();++i) ^