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: Wrong Answer)

def func(s, c, d = 1)
  t = '*' * (s.size - 1)
  k = 0

  (s.size - 1).times do |i|
    if s[i] == c then
      t[i] = c
    elsif s[i + 1] == c then
      t[i] = c
    else
      t[i] = s[i]
      k += 1
    end
  end

  return (k == 0) ? d : func(t, c, d + 1)
end

def main(argv)
  s = gets.chomp
  n = s.size

  m = 1e+9.to_i
  'abcdefghijklmnopqrstuvwxyz'.split('').each do |c|
    if s != (c * n) then
      m = [func(s, c), m].min
    end
  end
  puts m.to_s
end

if self.to_s == 'main' then
  main(ARGV)
end