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.split('')
h = Hash.new([])
0.upto(s.size - 1) do |i|
  h[s[i]] += [i]
end
def diffmax(ary, size)
  nary = [-1] + ary + [size]
  max = 0
  1.upto(nary.size-1) do |i|
    diff = nary[i] - nary[i-1] - 1
    max = diff if max < diff
  end
  max
end
min = 10**12
h.each do |k, v|
  diff = diffmax(v, s.size)
  min = diff if min > diff
end
puts min