/in/foo.cc:32:1: error: stray '`' in program
   32 | ```//别偷代码，用了的点个赞
      | ^
/in/foo.cc:32:2: error: stray '`' in program
   32 | ```//别偷代码，用了的点个赞
      |  ^
/in/foo.cc:32:3: error: stray '`' in program
   32 | ```//别偷代码，用了的点个赞
      |   ^
/in/foo.cc: In function 'int pd(std::string)':
/in/foo.cc:10:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |     for(int i=0;i<s.size();i++)
      |                 ~^~~~~~~~~