(load "1_28.sch")	; for prime?

(define (filtered-accumulate combiner null-value pred term a next b)
  (if (> a b)
    null-value
    (combiner
      (if (pred a) (term a) null-value)
      (filtered-accumulate combiner null-value pred term (next a) next b))))

(define (square x) (* x x))

(define (gcd a b)
  (if (= b 0)
    a
    (gcd b (remainder a b))))

(define (rel-prime a b)
  (= (gcd a b) 1))

(define (sum-squares-primes a b)
  (filtered-accumulate
    (lambda (x y) (+ x y))
    0
    prime?
    square
    a
    (lambda (x) (+ 1 x))
    b))

(define (prod-rel-prime n)
  (filtered-accumulate
    (lambda (x y) (* x y))
    1
    (lambda (x) (rel-prime x n))
    (lambda (x) x)
    1
    (lambda (x) (+ 1 x))
    n))