A program to swap two number without using 3rd variable in C

A program to swap two number without using third variable:

****************************program**************************************** 

#include<stdio.h>
#include<conio.h>
int main()
{
 int num1,num2;
 printf("\n enter the 1st number:");
 scanf("%d",&num1);
 printf("\n enter the 2nd number:");
 scanf("%d",&num2);
 printf("\n the  digits of the num1 is %d & num2 is %d",num2,num1);
 getch();
}

****************************output*****************************************

out put of the program to swap of two num with out using 3rd variable