what is the values of u, v, w and z at the end of execution.

abstract class A { int val = 1; int foo (int x); } abstract class B extending A { int val = 2; } class C extending B { int n = 0; int foo (int x){ return x+val+n; } } class D extending C { int n; D(int v){ n=v; } int foo (int x){ return x+val+n; } }

public class binmeth { public static void main (String [] args) { int u, v, w, z; A a; B b; C c; D d = new D(3); a = d; b = d; c = d; u = a.foo(1); v = b.foo(1); w = c.foo(1); z = d.foo(1); System.out.print(u); } }