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.IO;
using System.Diagnostics;
using System.Linq;
using System.Collections.Generic;
using static System.Math;

class P
{
    static void Main()
    {
        string s = Console.ReadLine();
        char[] cs = s.Distinct().ToArray();
        int min = int.MaxValue;
        foreach (var c in cs)
        {
            char[] vs = s.ToArray();
            int count = 0;
            while (vs.Distinct().Count() != 1)
            {
                char[] newv = new char[vs.Length - 1];
                for (int i = 0; i < newv.Length; i++)
                {
                    if (vs[i] == c || vs[i + 1] == c) newv[i] = c;
                    else newv[i] = vs[i];
                }
                vs = newv;
                Debug.WriteLine(string.Join(" ",vs));
                count++;
            }
            min = Min(min, count);
        }
            Console.WriteLine(min);
    }
}