Program to swap two numbers without using third variable using C

Program to swap two numbers without using third variable:

#include <stdio.h>
int main()   
{   
    int number1=15, number2=25;     
    printf("Intially number1=%d number2=%d",number1,number2);     
    number1=number1+number2;//number1=40 (15+25)   
    number2=number1-number2;//number2=15 (40-25)   
    number1=number1-number2;//number1=25 (40-15)   
    printf("\nAfter swap number1=%d number2=%d",number1,number2);   
    return 0; 
}

Output:
Intially number1=15 number2=25                                                                                               
After swap number1=25 number2=15