public class Assertions1 {
    public static void foo(int x) {
        Scanner console = new Scanner(System.in);
        
        System.out.print("You must type a value > 0: ");
        int val = console.nextInt();
        int z = 0;
        
        // Point A
        while (val > 0) {
            // Point B
            z += val;
            if (x > 0) {
                val--;
            } else {
                z -= val;
                x = -1 * x + 1;
                // Point C
            }
            // Point D
        }
        // Point E
    }
}

/* SOLUTION:

            x > 0       z == 0      val > 0
Point A     S           A           S
Point B     S           S           A
Point C     A           A*          A
Point D     A           S           S
Point E     S           S           N

* This was an error in lecture. The correct answer is Always, because
the only time that you could go into the else is the first time through
the loop, in which case z was val before the else, and gets reset to 0
inside the else.

*/