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 Ruby (2.3.3) (judge verdict: Accepted)

S = gets.chomp

ans = Float::INFINITY

ans = 0 if S.chars.uniq.size == 1

S.chars.uniq.each do |ch|
  s = S.dup
  flg = true

  while flg
    temp = s.dup
    str = ''
    flg = false

    0.upto(temp.size - 2) do |i|
      if s[i] == ch || s[i + 1] == ch
        str << ch
      else
        str << s[i]
        flg = true
      end
    end

    s = str
  end

  cnt = S.size - s.size

  ans = cnt if ans > cnt
end

puts ans