foo.cc: In function 'int bfs_1(int, int, int*, int*)':
foo.cc:58:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |         for (int i=0;i<cw[now].size();i++)
      |                      ~^~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:98:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   98 |         for (int i=0;i<cw.size();i++)
      |                      ~^~~~~~~~~~
foo.cc:108:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  108 |             scanf("%d",&x);
      |             ~~~~~^~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务