(define (task1 spisok)
  (define (iter1 sp0 sp1 sp2 lis)
    (if (or (empty? sp0) (empty? sp1) (empty? sp2)) lis
        (iter1 (cdr sp0) (cdr sp1) (cdr sp2) (cons (list (car sp0) (car sp1) (car sp2)) lis))))
  (define (iter sp0 sp1 sp2 spisok)
    (if (empty? spisok) (iter1 sp0 sp1 sp2 null)
        (iter (if (= (remainder (car spisok) 3) 0) (cons (car spisok) sp0) sp0) (if (= (remainder (car spisok) 3) 1) (cons (car spisok) sp1) sp1) (if (= (remainder (car spisok) 3) 2) (cons (car spisok) sp2) sp2) (cdr spisok))))
  (iter null null null spisok))




(define task2 1)

(define (task3 bind)
  (define l (flatten bind))
  (define (iter li s n)
    (if (empty? li) n
        (if (> (car li) s) (iter (cdr li) (car li) 1)
            (iter (cdr li) s (+ (if (= s (car li))1 0) n)))))
  (iter l (car l) 0))





(define (task4 bind)
  (if (empty? bind) 0
      (if (and (empty? (cadr bind)) (empty? (caddr bind))) 1
          (+ (task4 (cadr bind)) (task4 (caddr bind))))))

(define (task5 bind)
  (if (empty? bind) #f
      (if (and (empty? (cadr bind)) (empty? (caddr bind))) #t
          (and (task5 (cadr bind)) (task5 (caddr bind))))))