Swapping of two numbers without using third variable

//Swapping of two numbers without using third variable.

#include<stdio.h>
#include<conio.h>

void main()
{
  int a,b;
  clrscr();
  printf("Enter the value of a:");
  scanf("%d",&a);
  printf("Enter the value of b:");
  scanf("%d",&b);
  b=a+b;
  a=b-a;
  b=b-a;
  printf("After swapping:\n");
  printf("a=%d and b=%d",a,b);
 
  getch();
}

Output:

Enter the value of a:5
Enter the value of b:4
After swapping:
a=4 and b=5