Factorial zeros

Description:

Input:

The only line of input contains an integer n (1 ≤ n ≤ 1000000).

Output:

Output the number of trailing zeros in n!.

Sample Input:

6

Sample Output:

1

Sample Input:

24

Sample Output:

4

Note:

In the first sample 6! = 720.

In the second sample 24! = 620448401733239439360000.