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: Wrong Answer)

<?php
$str = trim(fgets(STDIN));
$longest = 0;
for($a = 'a'; $a !='aa'; $a++){
  $s = $str;
  for($n = strlen($str) - 1; $n >= 1; $n--){
    $ok = true;
    for($i = 0; $i < $n+1; $i++){
      if($s[0] <> $s[$i]){
        $ok = false;
      }
    }
    if($ok){
      $longest = max($longest, strlen($s));
      break;
    }
    $s2 = "";
    for($i = 0; $i < $n; $i++){
      $s2[$i] = $s[$i];
      if($s[$i + 1] == $a){
        $s2[$i] = $s[$i + 1];
      }
    }
    $s = $s2;
  }
}
echo strlen($str) - $longest, "\n";