sicp-2e/c1/e1.14.scm

(define (first-denomination kinds-of-coins)
    (cond ((= kinds-of-coins 1) 1)
          ((= kinds-of-coins 2) 5)
          ((= kinds-of-coins 3) 10)
          ((= kinds-of-coins 4) 25)
          ((= kinds-of-coins 5) 50)))

(define (cc amount kinds-of-coins)
    (display "a")
    (cond ((= amount 0) 1)
          ((or (< amount 0) (= kinds-of-coins 0)) 0)
          (else (+ (cc amount (- kinds-of-coins 1))
                   (cc (- amount
                          (first-denomination kinds-of-coins))
                       kinds-of-coins)))))

(define (count-change amount)
    (cc amount 5))

(count-change 100)