(define zero (lambda (f) (lambda (x) x)))
(define one (lambda (f) (lambda (x) (f x))))
(define plus (lambda (m n) (lambda (f) (lambda (x) ((n f) ((m f) x))))))
(define mult (lambda (m n) (lambda (f) (lambda (x) ((n (m f)) x)))))
(define xp (lambda (m n) (lambda (f) (lambda (x) (((n m) f) x)))))
(define inc (lambda (x) (+ x 1)))
(define num (lambda (n) ((n inc) 0)))
(define two (plus one one))
(define three (plus two one))
(define six (mult two three))
(define sixty-four (xp two six))
(num sixty-four)