/in/foo.cc: In function 'int bfs_1(int, int)':
/in/foo.cc:36:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |         for (int i=1;i<c.size();i++)
      |                      ~^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:78:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |         for (int i=0;i<c.size();i++)
      |                      ~^~~~~~~~~