CF102B.Sum of Digits

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?

看完最后一部《哈利·波特》电影后，小杰拉尔德也决定练习魔法。他在父亲的魔法书中发现了一个咒语：能将任意数字变为它的各位数字之和。就在杰拉尔德学到这个咒语时，他遇到了一个数字 $n$。杰拉尔德最多可以对它施放多少次该咒语，直到这个数字变成一位数？

The first line contains the only integer n (0 ≤ n ≤ 10100000). It is guaranteed that n doesn't contain any leading zeroes.

第一行包含唯一一个整数 $n$（$0 \leq n \leq 10^{100000}$）。保证 $n$ 不含前导零。

Print the number of times a number can be replaced by the sum of its digits until it only contains one digit.

打印一个数字可以被其各位数字之和替换的次数，直到该数字仅包含一位数字为止。

In the first sample the number already is one-digit — Herald can't cast a spell.

The second test contains number 10. After one casting of a spell it becomes 1, and here the process is completed. Thus, Gerald can only cast the spell once.

The third test contains number 991. As one casts a spell the following transformations take place: 991 → 19 → 10 → 1. After three transformations the number becomes one-digit.

在第一个样例中，该数字本身已是一位数——Herald 无法施放法术。

第二个测试用例包含数字 10。施放一次法术后，它变为 1，此时过程结束。因此，Gerald 只能施放一次法术。

第三个测试用例包含数字 991。每次施放法术时，依次发生如下变换：991 → 19 → 10 → 1。经过三次变换后，该数字变为一位数。