CF888C K-Dominant Character

You are given a string $ s $ consisting of lowercase Latin letters. Character $ c $ is called $ k $ -dominant iff each substring of $ s $ with length at least $ k $ contains this character $ c $ . You have to find minimum $ k $ such that there exists at least one $ k $ -dominant character.

The first line contains string $ s $ consisting of lowercase Latin letters ( $ 1

Print one number — the minimum value of $ k $ such that there exists at least one $ k $ -dominant character.