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 Go (1.6) (judge verdict: Accepted)

package main

import "fmt"

func main() {
	var s string
	fmt.Scan(&s)
	dic := make([]map[rune]bool, len(s))
	flg := false

	for i := range s {
		dic[i] = make(map[rune]bool)
		dic[i][rune(s[i])] = true
	}
	for {
		for c := 'a'; c <= 'z'; c++ {
			for i := 0; i < len(dic); i++ {
				if !dic[i][rune(c)] {
					goto exitLoop
				}
			}
			flg = true
		exitLoop:
		}
		for i := 0; i < len(dic)-1; i++ {
			for j := range dic[i+1] {
				dic[i][j] = true
			}
		}
		if flg {
			break
		}
		dic = dic[:len(dic)-1]
	}
	fmt.Println(len(s) - len(dic))
}