/in/foo.cc: In function 'int main()':
/in/foo.cc:40:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j=0;j<G[i].size();j++)mat[i][G[i][j]]=1.0;
                ~^~~~~~~~~~~~
/in/foo.cc:41:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j=0;j<G[i].size();j++){
                ~^~~~~~~~~~~~