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)

def sim(s, to)
  ss = s

  res = 0
  while ss.chars.uniq.size > 1
    new_ss = ""
    (0...(ss.size-1)).each do |i|
      if ss[i] == to || ss[i+1] == to
        new_ss << to
      else
        new_ss << ss[i]
      end
    end
    ss = new_ss
    res += 1
  end
  
  res
end

s = gets.chomp
ans = 100000
s.chars.uniq.each do |c|
  ans = [ans, sim(s, c)].min
end
puts ans