foo.cc: In function 'void dfs(int, int)':
foo.cc:13:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |      for(int i = 0;i < way.size();i ++) {
      |                    ~~^~~~~~~~~~~~
foo.cc:15:15: 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 |          if(i < way.size() - 1) cout << "-";
      |             ~~^~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务