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)

S = list(input())
n = len(S)

dict = {}
i = 0
for c in S:
    if c not in dict:
        dict[c] = [False for _ in range(n)]
    dict[c][i] = True
    i += 1

suniq = set(S)

k = 0
for _ in range(n):
    end = False
    for c in suniq:
        end_c = True
        for j in range(len(dict[c]) - k):
            if not dict[c][j]:
                end_c = False
        if end_c:
            end = True
    if end:
        break
    
    k += 1

    for c in suniq:
        for j in range(len(dict[c]) - 1):
            if dict[c][j + 1]:
                dict[c][j] = True
    
print(k)