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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        var s = Console.ReadLine();
        var ans = 1145141919;

        for (var c = 'a'; c <= 'z'; c++)
        {
            var cnt = Count(s, c);
            ans = cnt < ans ? cnt : ans;
        }

        Console.WriteLine(ans);
        return;
    }

    static int Count(string s, char c)
    {
        for (var i = 0; ; i++)
        {
            if (s.GroupBy(x => x).Count() == 1) return i;

            var t = new char[s.Length - 1];

            for (var j = 0; j < s.Length - 1; j++)
            {
                if (s[j] == c) t[j] = s[j];
                else t[j] = s[j + 1];
            }

            s = new string(t);
        }
    }
}