#include<iostream>
using namespace std;
void swap(int & a, int & b);
int main(int argc, char const *argv[])
{
    int x1(5);
    int x2(7);
    swap(x1,x2);
    cout<<x1<<" "<<x2<<endl;
    system("pause");
    return 0;
}

void swap(int & a, int & b)
{
    int t;
    t = a;
    a = b;
    b = t;

}