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 (3.4.3) (judge verdict: Accepted)

from collections import Counter

s = input()
s_len = len(s)
c = Counter(s)
ans = float('inf')
for k in c.keys():
    tmp = list(s)
    cnt = 0
    while True:
        if len(set(tmp)) == 1:
            break
        for i in range(len(tmp)-1):
            if tmp[i] == k:
                tmp[i] = k
            elif tmp[i+1] == k:
                tmp[i] = k
            else:
                continue
        else:
            tmp = tmp[:-1]
            cnt += 1
    ans = min(ans,cnt)
print(ans)