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;

public class Hello
{
    public static void Main()
    {
        var aL = "abcdefghijklmnopqrstuvwxyz";
        var s = Console.ReadLine().Trim();
        var ret = 999999999;
        for (int i = 0; i < aL.Length; i++)
            ret = Math.Min(ret, getChange(s, aL[i]));
        Console.WriteLine(ret);
    }
    public static int getChange(string s, char c)
    {
        var ret = 0;
        while (true)
        {
            var cc = s.Replace(c.ToString(), "").Length;
            if (cc == 0) return ret;
            var ns = "";
            for (int i = 0; i < s.Length - 1; i++)
                if (s[i] == c | s[i + 1] == c) ns += c;
                else ns += s[i];
            ret++;
            s = ns;
        }
    }
}