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: Runtime Error)

using System;
using System.Linq;

class Solution
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine());
        var cat = Console.ReadLine().Split().Select(int.Parse).ToArray();

        var max = cat.Max();
        var maxCount = cat.Count(c => c == max);
        var min = cat.Min();
        var minCount = cat.Count(c => c == min);

        bool ok = false;
        if (max == min)
        {
            // 3 3 3 3 3 3      5 5 5 5 5 5
            // a b c a b c      a b c d e f
            if (2 * max <= n || max == n - 1)
            {
                ok = true;
            }
        }
        else if (max == min + 1)
        {
            // 3 3 4 4 4 4
            // a b c d c d
            if (2*(max - minCount) <= maxCount)
            {
                ok = true;
            }
        }

        Console.WriteLine(ok ? "Yes" : "No");
    }
}