import java.io.*;

public class SwapTwoNumbers{
    public static void main(String args[]){
        int x = 10;
        int y = 20;
        
        //before
        System.out.println("Before: x = "+x+"\ty = "+y);
        
        //swap
        x = x + y;
        y = x - y;
        x = x - y;
        
        //after
        System.out.println("After: x = "+x+"\ty = "+y);
    }
}
Swap two numbers without using third variable