Compilare: user.cpp: In function ‘void dfs(long int)’: user.cpp:31:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<a[i].size();j++) ^ user.cpp: In function ‘void dfs2(long int, long int)’: user.cpp:41:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<b[i].size();j++) ^ user.cpp: In function ‘int main()’: user.cpp:91:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<c2[i].size();j++) ^