/in/foo.cc: In function 'void SPFA(long long int)':
/in/foo.cc:45:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
   if(vis[t]>=2)
     ^
/in/foo.cc:53:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<G[t].size();i++){
               ~^~~~~~~~~~~~