100% swapping 2 numbers without using third variable

//program to swap two numbers without using third variable  
#include <stdio.h>
void main()
{
     int p,q;
     printf("\n enter two integers:");
     scanf("%d%d",&p,&q);
     printf("\n values of p and q before swapping are %d and %d respectively",p,q);  //suppose p=5, q=2
     p=p+q; //afterthis is run, p=7 and q=2
     q=p-q; //after this is run p=7 and q=5
     p=p-q; //afterthis is run p=2 and q=5
     printf("\n values of p and q after swapping are %d and %d respectively",p,q);    }

output ఇలా వచ్చె 

enter two integers:5 2
values of p and q before swapping are 5 and 2 respectively
 values of p and q after swapping are 2 and 5 respectively

Note: 

పొరపాటున పైన  కోడ్లో చివరిరెండు printf లలో  %d ల బదులు %f లు పెడితే  అప్పుడు https://www.programiz.com/c-programming/online-compiler/  లో   ఔట్పుట్ ఈ క్రింది విధంగా వచ్చె

 enter two integers:7 2

values of p and q before swapping are 0.000000 and 0.000000 respectively
values of p and q after swapping are 0.000000 and 0.000000 respectively