how write a program to swaping any two number without using 3rd variable ?

#include<stdio.h>

#include<conio.h>

void main()

{

int a,b;

clrscr();

printf("\n\t Enter the any value of A \t:\t");

scanf("%d",&a);

printf("\n\t Enter the any value of B \t:\t");

scanf("%d",&b);

a=a+b;

b=a-b;

a=a-b;

printf("\n\t After swaping the value of A is\t:\t%d",a);

printf("\n\t After swaping the value of B is\t:\t%d",b);

getch();

}