foo.cc: In function 'void dfs_ans(int, int)':
foo.cc:55:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   55 |     for (int i = 0; i < op1[x].size (); i ++ ) c1[op1[x][i]] ++ ;
      |                     ~~^~~~~~~~~~~~~~~~
foo.cc:56:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |     for (int i = 0; i < dop1[x].size (); i ++ ) c1[dop1[x][i]] -- ;
      |                     ~~^~~~~~~~~~~~~~~~~
foo.cc:57:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |     for (int i = 0; i < op2[x].size (); i ++ ) c2[op2[x][i] + n] ++ ;
      |                     ~~^~~~~~~~~~~~~~~~
foo.cc:58:23: 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 < dop2[x].size (); i ++ ) c2[dop2[x][i] + n] -- ;
      |                     ~~^~~~~~~~~~~~~~~~~

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