#include <algorithm>
#include <iostream>
#include <string>

int main()
{
  std::string s = "HALLO, Welt";
  std::string gut;      // ins Toepfchen
  std::string schlecht; // ins Kroepfchen
	
  std::partition_copy(begin(s), end(s), 
    std::back_inserter(gut),
    std::back_inserter(schlecht),
    [](char c) {return c <= 'Z';});
	
  std::cout << gut << " : " << schlecht << '\n';
}