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 PyPy3 (7.3.0) (judge verdict: Accepted)

import copy
char = list(map(chr, range(ord('a'), ord('z')+1)))
target = list(input())
ans = float("inf")
for c in char:
  s = copy.deepcopy(target)
  tmpans = 0
  while True:
    flag = True
    for si in s:
      if si != s[0]:
        flag = False
    if flag==True:
      break
    for i in range(len(s)-1):
      if s[i] == c or s[i+1] == c:
        s[i] = c
    s.pop()
    tmpans += 1
  if ans > tmpans:
    ans = tmpans
print(ans)