Problems
Repeat: how many times to repeat?
Repeat: how many times to repeat?
The positive integer number \textbf{N} is given. We subtract from this number the sum of its digits. From the received number we soon subtract the sum of its digits and so on. This operation continues until the number is positive. How many times this operation will be repeated?
\InputFile
The number \textbf{N}, \textbf{0} < \textbf{N} ≤ \textbf{2147483647}.
\OutputFile
The number of performed operations.
Input example #1
21
Output example #1
3