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 Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
    val s = readLine()!!
    var dic = Array(s.length) { mutableSetOf<Char>() }
    var flg = false

    for (i in 0 until s.length) {
        dic[i] = mutableSetOf(s[i])
    }

    while (true) {
        for (c in 'a'..'z') {
            var i = 0
            while (i < dic.size) {
                if (!dic[i].contains(c)) {
                    break
                }
                i++
            }
            if (i == dic.size) {
                flg = true
            }
        }
        for (i in 0 until dic.size - 1) {
            for (v in dic[i + 1]) {
                dic[i].add(v)
            }
        }
        if (flg) {
            break
        }
        dic = dic.slice(0 until dic.size - 1).toTypedArray()
    }
    println(s.length - dic.size)
}