Problems

# How many times to repeat?

The positive integer 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?

#### Input

One number n (0 < n < 2 * 109).

#### Output

The amount of performed operations.

Time limit 2 seconds
Memory limit 64 MiB
Input example #1
21

Output example #1
3