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

Example Output

5

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