# 上海高校程序设计邀请赛（华东理工大学专场）

F. N!

Give you an integer $n$, find the maximum $k$ that satisfies
$$n! \bmod 10^k = 0$$

### 输入格式

There are several test cases, please process till EOF.

For each test case, there is only one line contains integer $n$ $(1 \leq n \leq 10^9)$.

### 输出格式

For each test case, output the answer in one line.

### 样例

Input
2
5

Output
0
1


NaN