Problem Statement

出處: cses

Your task is to calculate the number of trailing zeros in the factorial $n!$.

For example, $20!=2432902008176640000$ and it has $4$ trailing zeros.

Input

The only input line contains an integer $n$.

• $1 \le n \le 10^15$

Output

Print the number of trailing zeros in $n!$.

Example

20

4

• 2026.10.04 更改測資範圍且加強測資後 rejudge