// An puzzle.   Figure out what enigma(x,y) does and prove it.

#include <iostream>
#include <cassert>

void enigma(int &x, int &y)
{
	x=y-x;
	y=y-x;
	x=x+y;
}

int main()
{
	int x=1;
	int y=2;
	enigma(x,y);
	cout << "x="<<x<<", y="<<y<<".";
}