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)

	ans := int(1e9)
	for i := 0; i < 26; i++ {
		c := byte('a' + i)

		cnt := 0
		cur := s
		for {
			ok := true
			for j := 0; j < len(cur); j++ {
				if cur[j] != c {
					ok = false
				}
			}
			if ok {
				break
			}

			cnt++
			tmp := ""
			for j := 0; j < len(cur)-1; j++ {
				if cur[j] == c || cur[j+1] == c {
					tmp += string(c)
				} else {
					tmp += string(cur[j])
				}
			}
			cur = tmp
		}

		if ans > cnt {
			ans = cnt
		}
	}

	fmt.Println(ans)
}