Given a number find the number of trailing zeroes in its factorial.

Input Format

A single integer - N

Output Format

Print a single integer which is the number of trailing zeroes.

Input Constraints

1 ≤ N ≤ 1000

Problem Setter: Practo Tech Team

SAMPLE INPUT
10

SAMPLE OUTPUT
2

Explanation

10! = 3628800 has 2 zeros in the end.

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