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"
	"strings"
)

func main() {
	var s string
	fmt.Scan(&s)
	ans := 100
	for v := 'a'; v <= 'z'; v++ {
		if strings.Contains(s, string(v)) {
			sum := fa(s, v)
			if sum < ans {
				ans = sum
			}
		}
	}
	fmt.Println(ans)
}

func fa(s string, v rune) int {
	sum := 0
	for len(s) != strings.Count(s, string(v)) {
		sum++
		temp := ""
		for i := 1; i < len(s); i++ {
			if rune(s[i]) == v || rune(s[i-1]) == v {
				temp += string(v)
			} else {
				temp += string(s[i])
			}
		}
		s = temp
	}
	return sum
}