/in/foo.cc: In function 'bool judge(int)':
/in/foo.cc:30:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<g[x].size() ;i++)
               ~^~~~~~~~~~~~
/in/foo.cc: In function 'void SPFA(int)':
/in/foo.cc:63:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<g[x].size() ;i++)
               ~^~~~~~~~~~~~