(defun main ()
  (let* ((n (read))
         (primes '(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47))
         (m 1)
         (count 0))
    (loop for p in primes
          while (<= m n)
          do (progn
               (setf m (* m p))
               (incf count)))
    (if (> m n)
        (decf count))
    (format t "~D~%" count)))

(main)