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: Accepted)

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Scanner;

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

    char[] s = scanner.next().toCharArray();
    List<Integer>[] pos = new List[26];
    for (int i = 0; i < 26; i++) {
      pos[i] = new ArrayList<>();
    }
    for (int i = 0; i < s.length; i++) {
      pos[s[i] - 'a'].add(i);
    }
    int min = s.length;
    for (int i = 0; i < 26; i++) {
      if (pos[i].isEmpty()) continue;
      int max = 0;
      int p = 0;
      Iterator<Integer> iter = pos[i].iterator();
      while (iter.hasNext()) {
        int q = iter.next();
        max = Math.max(max, q - p);
        p = q + 1;
      }

      max = Math.max(max, s.length - p);
      min = Math.min(min, max);
    }
    System.out.println(min);
  }
}