Get Minimum Operation Count

Replace as few characters as possible so that any two adjacent characters are neither equal nor adjacent letters in the alphabet. Use only lowercase a to z; a and z are not adjacent.

输入格式

One line containing a lowercase string, 2≤length≤100000.

输出格式

Output one integer, the answer.

样例 1

输入：

abdde

输出：

2

样例 2

输入：

ab

输出：

1

样例 3

输入：

az

输出：

0

样例说明

The examples give 2, 1 and 0 respectively.