tickets.cpp: In function 'long long int find_maximum(int, std::vector<std::vector<int> >)':
tickets.cpp:9:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    9 |     for(int i=0;i<x1.size();i++)
      |                 ~^~~~~~~~~~
tickets.cpp:12:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |         for(int j=0;j<x1[i].size();j++)row.push_back(x1[i][j]);
      |                     ~^~~~~~~~~~~~~
tickets.cpp:27:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |     for(int i=0;i<answer.size();i++)
      |                 ~^~~~~~~~~~~~~~
tickets.cpp:29:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |         for(int j=0;j<answer[i].size();j++)
      |                     ~^~~~~~~~~~~~~~~~~
tickets.cpp:48:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |     for(int i=0;i<xs.size()/2;i++)target-=xs[i].first;
      |                 ~^~~~~~~~~~~~
tickets.cpp:50:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   50 |     for(int i=xs.size()/2;i<xs.size();i++)target+=xs[i].first;
      |                           ~^~~~~~~~~~
tickets.cpp:51:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   51 |     for(int i=0;i<xs.size();i++)
      |                 ~^~~~~~~~~~
tickets.cpp:84:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |         for(int j=0;j<v.size();j++)
      |                     ~^~~~~~~~~
tickets.cpp:19:9: warning: variable 'ptr1' set but not used [-Wunused-but-set-variable]
   19 |     int ptr1[n],ptr2[n];
      |         ^~~~
tickets.cpp:19:17: warning: variable 'ptr2' set but not used [-Wunused-but-set-variable]
   19 |     int ptr1[n],ptr2[n];
      |                 ^~~~