foo.cc: In function 'void dfs_ori(int)':
foo.cc:29:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |   for (int i = 0; i < G_ori[x].size(); i++)
      |                   ~~^~~~~~~~~~~~~~~~~
foo.cc: In function 'void dfs_trans(int)':
foo.cc:44:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |   for (int i = 0; i < G_trans[x].size(); i++)
      |                   ~~^~~~~~~~~~~~~~~~~~~
foo.cc: In function 'int dfs_sum(int)':
foo.cc:58:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |   for (int i = 0; i < G_shrink[x].size(); i++)
      |                   ~~^~~~~~~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:127:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  127 |     for (int j = 0; j < G_ori[i].size(); j++)
      |                     ~~^~~~~~~~~~~~~~~~~

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