;;; ACK -- One of the Kernighan and Van Wyk benchmarks.

(import (rnrs base)
        (rnrs io simple))

(define (ack m n)
  (cond ((= m 0) (+ n 1))
        ((= n 0) (ack (- m 1) 1))
        (else (ack (- m 1) (ack m (- n 1))))))

(define (main)
  (let* ((count (read))
         (input1 (read))
         (input2 (read))
         (output (read))
         (s2 (number->string input2))
         (s1 (number->string input1))
         (name "ack"))
    (run-r6rs-benchmark
     (string-append name ":" s1 ":" s2)
     count
     (lambda () (ack (hide count input1) (hide count input2)))
     (lambda (result) (= result output)))))