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.Linq;
using System.Collections.Generic;

class P
{
    static void Main()
    {
        string s = Console.ReadLine();
        int[][] p = new int[26][];
        bool[][] b = new bool[26][];
        for (int i = 0; i < 26; i++)
        {
            b[i] = new bool[s.Length];
        }
        for (int i = 0; i < s.Length; i++)
        {
            b[s[i] - 'a'][i] = true;
        }
        for (int i = 0; i < 26; i++)
        {
            p[i] = new int[s.Length];
            if (!b[i][s.Length - 1]) p[i][s.Length - 1] = 1;
            for (int j = s.Length - 2; j >= 0; j--)
            {
                if (b[i][j]) p[i][j] = 0;
                else p[i][j] = p[i][j + 1] + 1;
            }
        }
        Console.WriteLine(p.Select(x => x.Max()).Min());
    }
}