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 (2.7.1) (judge verdict: Accepted)

s = gets.chomp

min = 100
# 最大26回
s.split("").uniq.each do |c|
  count = 0
  str = s.dup
  # cに全部変える操作を行う(ループは100回以下)
  while true do
    break if str.split("").uniq.length <= 1
    count += 1
    0.upto(s.length-2) do |i| # (ループは100回以下)
      if str[i] == c || str[i+1] == c
        str[i] = c
      end
    end
    str.chop! # 末尾削除
  end
  min = count if count < min
end
puts min