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 Scala (2.11.7) (judge verdict: Time Limit Exceeded)

import java.util.Scanner

object Main extends App {
  val sc = new Scanner(System.in)

  val s = sc.next
  val alphabets = "abcdefghijklmnopqrstuvwxyz"

  val res = alphabets.map(loop(_, s).max).min
  println(res)

  def loop(ch: Char, str: String, vec: Vector[Int] = Vector.empty): Vector[Int] = {
    str.foldLeft(vec){ case (acc, c) =>
      val (tr, fa) = str.span(_ != ch)
      if(fa.isEmpty) vec :+ tr.length
      else loop(ch, fa.tail, vec :+ tr.length)
    }
  }
}