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

int main()
{
  std::string s = "Harro, Wert";
  std::string t;
  std::cout << s << '\n';

  std::replace_copy(begin(s), end(s), std::back_inserter(t), 'r', 'l');

  std::cout << t << '\n';
}