Count the number of trailing zeros in $n!$.
Note: $n! = 1 \times 2 \times ... \times n$.
### Input
- The first line contains an integer $n$.
### Output
- A single integer is the number of traling zeros in $n!$.
### Constraints
- $1 \le n \le 1000$.
### Example
Input:
```
10
```
Output:
```
2
```
