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;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using static MyIO;


public class A
{
	public static void Main()
	{
		string s = GetString();
		var set = new HashSet<char>();
		for(int i = 0; i < s.Length; i++)
			set.Add(s[i]);
		if(set.Count == 1)
		{
			Console.Write(0);
			return;
		}
		var list = set.ToList();

		int ans = int.MaxValue;
		foreach(char c in list)
		{
			int tmp = 0;
			char[] current = s.ToCharArray();
			char[] next = new char[s.Length];
			while(true)
			{				
				var tmpSet = new HashSet<char>();
				for(int i = 0; i < s.Length - 1 - tmp; i++)
				{
					next[i] = current[i];
					if((i + 1 < s.Length - tmp) && (current[i + 1] == c))
						next[i] = c;
					tmpSet.Add(next[i]);
				}
				tmp++;
				current = next;

				if(tmpSet.Count == 1)
				{
					ans = Math.Min(ans, tmp);
					break;
				}
			}
		}
		Console.WriteLine(ans);
	}
}


public static class MyIO
{
	private static string[] args = null;
	private static int num = -1;
	private static int used = -1;

	private static string getArg()
	{
		if(used == num)
		{
			args = Console.ReadLine().Split(' ');
			num = args.Length;
			used = 0;
		}
		return args[used++];
	}

	public static int GetInt(){ return int.Parse(getArg()); }
	public static long GetLong(){ return long.Parse(getArg()); }
	public static double GetDouble(){ return double.Parse(getArg()); }
	public static string GetString(){ return getArg(); }
}