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;

namespace AtCoder.Grand016
{
    class A
    {
        static void Main(string[] args)
        {
            // 文字列の入力
            string input = Console.ReadLine();
            
            int maxDiffMin = int.MaxValue;

            char[] array = input.ToCharArray();
            for ( char c = 'a'; c <= 'z'; c++ )
            {
                if ( input.IndexOf( c ) == -1 )
                {
                    continue;
                }

                int maxDiff = 0;

                List<int> index = new List<int>();

                index.Add( -1 );

                int start = 0;
                while ( input.IndexOf( c, start ) != -1 )
                {
                    index.Add( input.IndexOf( c, start ) );
                    start = input.IndexOf( c, start ) + 1;
                }
                
                index.Add( input.Length );

                for ( int i = 0; i < index.Count - 1; i++ )
                {
                    maxDiff = Math.Max( index[i+1] - index[i] - 1, maxDiff );
                }

                maxDiffMin = Math.Min( maxDiffMin, maxDiff );

            }

            //出力
            Console.WriteLine( maxDiffMin );
            

#if DEBUG
            Console.WriteLine( "press Enter." );
            Console.ReadLine();
#endif

        }
        
    }
}