(define (main args)
  (let* ([a (read)]
         [b (read)]
         [c (read)]
         [d (read)]
         [e (read)]
         [noc (* a (- b c))])
    (print
     (let loop ([i 1]
                [pr d]
                [sm 0])
       (cond [(> i noc) sm]
             [(zero? (remainder i 10)) (if (<= e pr)
                                           (loop (+ i 1) (- pr e) (+ sm (- pr e)))
                                           (loop (+ i 1) pr (+ sm pr)))]
             [else (loop (+ i 1) pr (+ sm pr))]))))
  0)