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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner reader = new Scanner(System.in);

		String input = reader.next();

		Map<String, List<Integer>> data = new HashMap<>();

		int result = 1000000;

		for (int i = 1; i <= input.length(); i++) {
			String key = Character.toString(input.charAt(i - 1));
			Integer value = Integer.valueOf(i);

			if (data.containsKey(key)) {
				data.get(key).add(value);
			} else {
				data.put(key, new ArrayList<>(Arrays.asList(value)));
			}
		}

		boolean unique = true;

		for (Map.Entry<String, List<Integer>> entry : data.entrySet()) {
			if (entry.getValue().size() > 1) {
				unique = false;
			}
		}

		if (unique) {
			result = input.length() / 2;
		} else {
			for (Map.Entry<String, List<Integer>> entry : data.entrySet()) {
				Integer max = 0;
				Integer previous = 1;

				for (Integer i : entry.getValue()) {
					if (i - previous > max) {
						max = i - previous;
					}
					previous = i + 1;
				}

				if (input.length() - previous > max) {
					max = input.length() - previous;
				}

				if (result > max) {
					result = max;
				}
			}
		}

		System.out.println(result);

		reader.close();
	}
}