foo.cc: In function 'void bfs()':
foo.cc:45:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |         for(int i=0; i<a[u].size(); i++)
      |                      ~^~~~~~~~~~~~

Found 5 testcases.
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