CSES - Trailing Zeros
  • Time limit: 1.00 s
  • Memory limit: 512 MB
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 has an integer $n$.

Output

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

Constraints
  • $1 \le n \le 10^9$
Example

Input:
20

Output:
4