(use srfi-1)   ;; list library
(use math.prime)

(define (main args)
  (let* ([n (read)]
         [l (read)])
    (print (fold
            (^(x ct) (+ ct (- l (* x (- n 1)) -1)))
            0
            (take-while (^x (>= l (* x (- n 1)))) *primes*))))
  0)