foo.cc: In function ‘void fohuj()’:
foo.cc:19:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   19 |                 for(int i=0;i<b[x].size();i++)qa[b[x][i]]--;
      |                             ~^~~~~~~~~~~~
foo.cc:21:72: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   21 |                 for(int i=1;i<=n;i++){if(qa[i]==1){flag=1;for(int j=0;j<a[i].size();j++)if(!vis[a[i][j]]){p.push(a[i][j]);ans[i]=a[i][j];vis2[i]=1;qj++;break;}break;}if(qa[i]==0&&vis2[i]==0){cout<<"None";exit(0);}}
      |                                                                       ~^~~~~~~~~~~~