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.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String[] s = sc.next().split("");
		String[] v = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
		int ans = Integer.MAX_VALUE;
		for (int i = 0; i < 26; i++) {
			int tmp = 0;
			String[] u = s;
			loop: while (true) {
				boolean comp = true;
				for (int j = 0; j < u.length; j++)
					if (!u[j].equals(u[0])) {
						comp = false;
						break;
					}
				if (comp) {
					ans = Math.min(ans, tmp);
					break loop;
				}
				String[] w = new String[u.length - 1];
				for (int j = 0; j < w.length; j++) {
					if (u[j].equals(v[i]) || u[j + 1].equals(v[i]))
						w[j] = v[i];
					else
						w[j] = u[j];
				}
				u = w;
				tmp++;
			}
		}
		System.out.println(ans);
	}
}