foo.cc: In function 'void dfs(int)':
foo.cc:23:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |                 for(int j=0;j<q[v].size();j++){
      |                             ~^~~~~~~~~~~~

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