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 Python (3.8.2) (judge verdict: Accepted)

import copy
import string

s = list(input())
ans = 0
if len(set(s)) == 1:
  print(0)
else:
  for k in string.ascii_lowercase:
    tmp = 0
    l = copy.deepcopy(s)
    while any(ss != k for ss in l):
      for i in range(len(l) - 1):
        if l[i + 1] == k:
          l[i] = k
      l.pop(-1)
      tmp += 1
    if ans:
      ans = min(ans, tmp)
    else:
      ans = tmp
  print(ans)