swapping without variable for turbo c in C

#include<stdio.h>
#include<conio.h>
void main()
{
int n,a,b;
clrscr();
printf("enter value of a\n");
scanf("a:-%d\t",&a);
printf("enter value of b\n");
scanf("b:-%d\t",&b);
a=a+b;
b=a-b;
a=a-b;
printf("after swapping a value is :- %d\t",a);
printf("after swapping b value is :- %d\t",b);
getch();
}