Compilare: user.cpp: In function ‘void dfs1(int)’: user.cpp:21:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[k].size();i++) ^ user.cpp: In function ‘void dfs2(int)’: user.cpp:27:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<b[k].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:47:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<q.size();i++) ^