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 $27 \rightarrow 20 \rightarrow 18 \rightarrow 10 \rightarrow 9 \rightarrow 0$.