WAP to swap the values of two integer variables, without using extra variable

#include <stdio.h>
int main ()
{
    int a,b;
    printf("Enter 1st number: ");
    scanf("%d",&a);
    printf("Enter 2nd number: ");
    scanf("%d",&b);
    printf("a = %d  b = %d\n",a,b);

    a=a+b;
    b=a-b;
    a=a-b;

    printf("After swaping a = %d  b = %d\n",a,b);
    return 0;
}