foo.cc: In function 'void dfs(int)':
foo.cc:18:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |         for (int i = 0; i < g[u].size(); i++) {
      |                         ~~^~~~~~~~~~~~~
foo.cc: In function 'void askring(int, int)':
foo.cc:37:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |         for (int i = 0; i < g[u].size(); i++) {
      |                         ~~^~~~~~~~~~~~~

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