Swap Numbers without Temporary Variable

#include<stdio.h>
void main()
// Swap Numbers without  Temporary Variable
{

    double a,b;
    printf("Enter first number:\n");
    scanf("%lf",&a);
    printf("Enter second number:\n");
    scanf("%lf",&b);
    a=a-b;
    b=a+b;
    a=b-a;
    printf("After swapping, first Number: %.0lf\n",a);
    printf("After swapping, second Number: %.0lf",b);


}