#| BEGIN (Введите свое решение) |#
(define (accumulate op initial sequence)
  (if (null? sequence)
      initial
      (op (car sequence) (accumulate op initial (cdr sequence)))))

(define (flatmap proc seq)
  (accumulate append '() (map proc seq)))

(define (enumerate-interval low high)
  (if (> low high)
      '()
      (cons low (enumerate-interval (+ low 1) high))))

(define (make-triple-sum n s)
  (filter (lambda (triple) (= (+ (car triple) (cadr triple) (caddr triple)) s))
          (flatmap (lambda (i)
                     (flatmap (lambda (j)
                                (map (lambda (k) (list i j k))
                                     (enumerate-interval 1 (- j 1))))
                              (enumerate-interval 2 (- i 1))))
                   (enumerate-interval 3 n))))
#| END |#