4121: CF102 - B. Sum of Digits
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Description
Having watched the last Harry Potter film, little Gerald also decided to practice magic.
He found in his father's magical book a spell that turns any number in the sum of its digits.
At the moment Gerald learned that, he came across a number $n$.
How many times can Gerald put a spell on it until the number becomes one-digit?
He found in his father's magical book a spell that turns any number in the sum of its digits.
At the moment Gerald learned that, he came across a number $n$.
How many times can Gerald put a spell on it until the number becomes one-digit?
Input
The first line contains the only integer $n\ (0≤n≤10^{100000})$.
It is guaranteed that n doesn't contain any leading zeroes.
It is guaranteed that n doesn't contain any leading zeroes.
Output
Print the number of times a number can be replaced by the sum of its digits until it only contains one digit.
Sample 1 Input
0
Sample 1 Output
0
The number already is one-digit − Herald can't cast a spell.
Sample 2 Input
10
Sample 2 Output
1
After one casting of a spell it becomes 1, and here the process is completed. Thus, Gerald can only cast the spell once.
Sample 3 Input
911
Sample 3 Output
3
As one casts a spell the following transformations take place: 991→19→10→1. After three transformations the number becomes one-digit.