swap numbers by using call by reference in C++

#include<iostream.h>
int swap(int &a, int &b)
{
int t=a;
a=b;
b=t;
}
int main()
{
int x=5; int y=67;
cout<<"Before swap : "<<x<<"\t"<<y<<"\n";
swap(x,y);
cout<<"\nAfter Swap: "<<x<<"\t"<<y<<"\n";
return 0;
}