You are given an integer ~N~. On each move, you may subtract one of the digits from the number.

What is the minimum number of moves to make the number equal to ~0~?

Input

• The only integer ~N~ ~(0 ≤ N ≤ 10^7)~.

Output

• The minimums number of moves.

Sample Input 1

18

Sample Output 1

3

Sample Input 2

20

Sample Output 2

4

Notes:

• Sample ~1~: ~18 \to 18~ – ~8 = 10\to10~ – ~1 = 9\to9~ – ~9 = 0~
• Sample ~2~: ~20\to18\to10\to9\to0~