CSES - Removing Digits
  • Time limit: 1.00 s
  • Memory limit: 512 MB
You are given an integer $n$. On each step, you may subtract one of the digits from the number.

How many steps are required to make the number equal to $0$?

Input

The only input line has an integer $n$.

Output

Print one integer: the minimum number of steps.

Constraints
  • $1 \le n \le 10^6$
Example

Input:
27

Output:
5

Explanation: An optimal solution is $27 \rightarrow 20 \rightarrow 18 \rightarrow 10 \rightarrow 9 \rightarrow 0$.