#include <iostream>
#include <string>
using namespace std;

void swap (string& s1,  string& s2);

int main(){

  string str1 = "Bruce", str2 = "Kat";

  cout << str1 << ' ' << str2 << endl;

  swap(str1, str2);

  cout << str1 << ' ' << str2 << endl;

  return 0;

}

void swap (string &s1,  string &s2){
 string temp = s1;
 cout << "swap: " << s1 << ' ' << s2 << endl;
 s1 = s2;
 s2 = temp;
 cout <<"swap: " << s1 << ' ' << s2 << endl;
}