#lang racket

(require "Lambda.rkt")

(define (MUL a b) (If (Empty? a) Z (helper a b Z)))

(define (helper a b c)
  (If (Empty? b) c
      (If (Car b) (helper (Cons False a) (Cdr b) (ADD c a))
          (helper (Cons False a) (Cdr b) c))))