Compilare: user.cpp: In function ‘void dfs1(int)’: user.cpp:10:30: 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:17:30: 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:41:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<c[i].size();j++) ^