Competitions

# PP1 and Competitive Programming

# Number of zeroes in factorial

Find the number of zeros at the end of **n**! (**n** factorial).

#### Input

One integer **n** (**1** ≤ **n** ≤ `2*10`

).^{9}

#### Output

Print the number of zeros at the end of **n**!

Input example #1

7

Output example #1

1

Input example #2

12

Output example #2

2