foo.cc: In function ‘void dijstra()’:
foo.cc:15:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<std::pair<int, int> >::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   15 |                 for(int i=0;i<e[now].size();i++)
      |                             ~^~~~~~~~~~~~~~