Decrementing to Zero

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Start from nonnegative x. At each step let d be the last decimal digit. If d>0, subtract d; otherwise subtract 1. Count steps until x first reaches zero. Starting at zero requires zero steps.

Input

One integer x.

Output

Print the number of operations.

Subtasks

• Subtask 1 (20%): $0\le x\le100$.
• Subtask 2 (30%): $0\le x\le10^4$.
• Subtask 3 (50%): $0\le x\le10^6$.

Examples

Example 1

Input

21

Output

5

Explanation

The states are 21,20,19,10,9,0: five operations.

Example 2

Input

0

Output

0

Explanation

Zero already satisfies the stopping condition.