/in/foo.cc: In function 'void bfs()':
/in/foo.cc:37:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<g[x].size();i++)
               ~^~~~~~~~~~~~
/in/foo.cc:38:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<g[y].size();j++)
               ~^~~~~~~~~~~~