Using reference variables as arguments

Write a function by using reference variables as arguments to sort two numbers in descending order.

#include <iostream>

using namespace std;
int swap(int &,int &);
int main(void)
{
    int x,y;
    cin >> x >> y;
    swap(x,y);
    cout << x << ' ' << y << endl;
    return 0;
}

int swap(int &x,int &y)
{
    int temp;
    if(x<y)
    {
        temp=x;
        x=y;
        y=temp;
    }
    return 0;
}