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**Task** | Statistics

Time limit: | 1.00 s | Memory limit: | 512 MB |

You are given an integer $n$. On each step, you may substract from it any one-digit number that appears in it.

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

The only input line has an integer $n$.

Print one integer: the minimum number of steps.

- $1 \le n \le 10^6$

Input:

`27`

Output:

`5`

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