Problem:
Score : 300 points

Problem Statement

Snuke can change a string t of length N into a string t' of length N - 1 under the following rule:

For each i (1 ≤ i ≤ N - 1), the i-th character of t' must be either the i-th or (i + 1)-th character of t.

There is a string s consisting of lowercase English letters.
Snuke's objective is to apply the above operation to s repeatedly so that all the characters in s are the same.
Find the minimum necessary number of operations.

Constraints

1 ≤ |s| ≤ 100

s consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

s

Output

Print the minimum necessary number of operations to achieve the objective.

Sample Input 1

serval

Sample Output 1

3

One solution is: serval → srvvl → svvv → vvv.

Sample Input 2

jackal

Sample Output 2

2

One solution is: jackal → aacaa → aaaa.

Sample Input 3

zzz

Sample Output 3

0

All the characters in s are the same from the beginning.

Sample Input 4

whbrjpjyhsrywlqjxdbrbaomnw

Sample Output 4

8

In 8 operations, he can change s to rrrrrrrrrrrrrrrrrr.

Solution in PHP7 (7.0.15) (judge verdict: Accepted)

<?php

    $s = trim(fgets(STDIN));
    $n = strlen($s);
    for($i=0; $i<26; $i++) $c[$i] = 0;
    for($i=0; $i<$n; $i++){
        $t[$i] = ord($s[$i])-ord('a');
    }
    
    $ans = 1000;
    for($c=0; $c<26; $c++){
        for($i=0; $i<$n; $i++) $u[$i] = $t[$i];
        $f = true;
        $x = $n;
        while($f){
            $f = false;
            for($i=0; $i<$x-1; $i++){
                if($u[$i] != $c){
                    $f = true;
                    if($u[$i+1] == $c) $u[$i] = $c;
                }
            }
            if($f) $x--;
            if(!$f && $u[$x-1] != $c) $x--;
        }
        if($n-$x<$ans) $ans = $n-$x;
    }
    echo $ans;
?>