/in/foo.cc: In function 'bool bfs(int)':
/in/foo.cc:65:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<g[ q[head] ].size();i++)
               ~^~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int spfa(int)':
/in/foo.cc:102:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<g[ q[head] ].size();i++)
               ~^~~~~~~~~~~~~~~~~~~~