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: Accepted)

object Main extends App {
  def count(str: String, main: Char): Int = {
    var t = str
    var count = 0

    while (!ok(t)) {
      t = t.zip(t.tail).map(_ match {
        case (`main`, _) => main
        case (_, `main`) => main
        case (cur, _) => cur
      }).mkString
      count = count + 1
    }
    count
  }

  def ok(str: String): Boolean = str.distinct.length <= 1

  def calc(str: String): Int = {
    str.map(c => count(str, c)).min
  }

  val sc = new java.util.Scanner(System.in)
  val str = sc.nextLine()
  println(calc(str))
}