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.Arrays;
import java.util.HashSet;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		new Main().solve();
	}

	void solve(){
		Scanner sc=new Scanner(System.in);
		String s=sc.next();
		
		int MinCount=100;
		for(int i=0;i<s.length();i++) {
			char target=s.charAt(i);
			
			String t2=s;
			int count=0;
			while(true) {
				String t1="";
				for(int j=0;j<t2.length()-1;j++) {
					if(t2.charAt(j)==target) {
						t1+=t2.charAt(j);
					}else if(t2.charAt(j+1)==target){
						t1+=t2.charAt(j+1);
					}else {
						t1+=t2.charAt(j);
					}
				}
				boolean flag=true;
				for(int j=0;j<t2.length()-1;j++) {
					if(t2.charAt(j)!=t2.charAt(j+1))flag=false;
				}
				if(flag)break;
				count++;
				t2=t1;
			}
			MinCount=Math.min(count, MinCount);
		}
		System.out.println(MinCount);
	}
}