foo.cc: In function ‘void dfs_ans(int, int)’:
foo.cc:48:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   48 |         for(int i=0;i<op1[x].size();i++) c1[op1[x][i]]++;
      |                     ~^~~~~~~~~~~~~~
foo.cc:49:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   49 |         for(int i=0;i<dop1[x].size();i++) c1[dop1[x][i]]--;
      |                     ~^~~~~~~~~~~~~~~
foo.cc:50:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   50 |         for(int i=0;i<op2[x].size();i++) c2[op2[x][i]+n]++;
      |                     ~^~~~~~~~~~~~~~
foo.cc:51:22: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   51 |         for(int i=0;i<dop2[x].size();i++) c2[dop2[x][i]+n]--;
      |                     ~^~~~~~~~~~~~~~~