/in/foo.cc: In function 'void toposort()':
/in/foo.cc:44:30: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |                 for(int i=0;i<g[u].size();i++)
      |                             ~^~~~~~~~~~~~