text: #pragma once
  
  #include <cstring>
  
  inline std::string strlower(const std::string &s)
  {
  	size_t l = s.length();
  	std::string sl = s;
  	for (size_t i = 0; i < l; i++)
  		sl[i] = tolower(sl[i]);
  	return sl;
  }
  