The factorial of a positive integer n, written as n!, is the product of the first n positive integers.  That is,</p>

n! = 1 × 2 × ... × n

Given a positive integer n, find the number of zeros in the decimal representation of n!.  Of course, leading zeros should not be counted.  (Note that decimal representation means base ten representation.)

입력 형식

The input contains a single positive integer n < 100.

출력 형식

The output contains a single integer giving the number of zeros in the decimal representation of n!.

예제 입력 1

20

예제 출력 1

7

예제 입력 2

7

예제 출력 2

2

예제 입력 3

4

예제 출력 3

0