Main.cc: In function ‘int quick_read()’:
Main.cc:12:5: error: ‘ch’ was not declared in this scope
   12 |     ch = getchar();
      |     ^~
Main.cc: In function ‘int main()’:
Main.cc:56:19: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<std::pair<int, int> >::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   56 |    for(int i = 0;i<res.size();i++){
      |                  ~^~~~~~~~~~~