A string of lowercase letters is called alphabetical if deleting zero or more of its letters can result in the alphabet string abcdefghijklmnopqrstuvwxyz.

Given a string ~s~, determine the minimum number of letters to insert anywhere in the string to make it alphabetical.

Input

The input consists of a single line containing the string ~s~ ~(1 \le \left|s\right| \le 50)~.

It is guaranteed that ~s~ consists of lowercase ASCII letters a to z only.

Output

Print, on a single line, a single integer indicating the minimum number of letters that must be inserted in order to make the string ~s~ alphabetical.

Sample Input 1

xyzabcdefghijklmnopqrstuvw

Sample Output 1

3

Sample Input 2

aiemckgobjfndlhp

Sample Output 2

20