/in/foo.cc: In function 'void bfs()':
/in/foo.cc:21:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |         for(int i = 0 ; i < g[t].size() ; i ++)
      |                         ~~^~~~~~~~~~~~~