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: Wrong Answer)

from collections import Counter

inputs = list(input())

count = 10 ** 15
kinds = len(set(inputs))
length = len(inputs)

def cal(inputs, item):
    re = ''
    for index in range(len(inputs)-1):
        if inputs[index] == item or inputs[index+1] == item:
            re += item
        else:
            re += inputs[index]
    return re

if kinds == length:
    count = length // 2 + length % 2
elif kinds == 1:
    pass
else:
    counter_inputs = Counter(inputs).most_common()
    filter_inputs = list(filter(lambda x:x[1]==counter_inputs[0][1], counter_inputs))
    counter_inputs.sort(key=lambda x:x[1], reverse=True)
    for counter_input in counter_inputs:
        item = inputs[:]
        total = 0
        while len(set(item)) != 1:
            item = list(cal(item, counter_input[0][0]))
            total += 1
        count = min(count, total)

print(count)