#!/usr/bin/env gosh

(use math.prime)
(use srfi-1)
(use srfi-42)

(define (count-seqs n l)
    (begin
        (define (x-max d) (- l (* d (- n 1))))
        (let ((d-max (div l (- n 1))))
            (sum-ec
                (: d (take-while
                    (lambda (x) (<= x d-max)) *primes*))
                (+ 1 (x-max d))))))

(let* ((n (read)) (l (read)))
    (print (count-seqs n l)))