JOI 2009 予選 4.scm

(use file.util)
(use util.combinations)
(use srfi-1)

(define (flatten-number xs)
  (string->number (apply string-append (map number->string xs))))

(let* ((input (map string->number (file->string-list "input.txt")))
       (k (second input))
       (nums (drop input 2)))
  (print (length+ (delete-duplicates (map flatten-number (append-map permutations (combinations nums k)))))))