foo.cc: In function ‘void dfs(ll)’:
foo.cc:13:21: warning: comparison of integer expressions of different signedness: ‘ll’ {aka ‘long long int’} and ‘std::vector<long long int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   13 |         for(ll i=0;i<q[x].v.size();i++)
      |                    ~^~~~~~~~~~~~~~

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