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 (2.4.0) (judge verdict: Accepted)

from copy import deepcopy as cp
s = input()
c = set(s)
ans = 10**9
for ch in c:
    #全ての文字をiにしよう！
    k = cp(s)
    cand = 0
    while len(set(k)) > 1:
        t = ""
        for i in range(len(k)-1):
            if k[i] == ch or k[i+1] == ch:
                t += ch
            else:
                t += k[i]
        cand += 1
        k = cp(t)
    ans = min(cand, ans)
print(ans)