foo.cc: In function ‘std::vector<std::pair<int, int> > geshu(std::vector<int>)’:
foo.cc:27:26: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   27 |         for(int num=0;num<result1.size();num++)
      |                       ~~~^~~~~~~~~~~~~~~