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)

S = input()
N = len(S)
maxim = (N + 1) // 2

def judge(cnt):
    k = N // (cnt + 1)
    flag = 1
    for i in range(cnt + 1):
        for j in range(1,k):
            if S[i] in S[j * (cnt + 1): j * (cnt + 1) + cnt + 1]:
                continue
            else: flag *= 0
        if flag == 1:
            return cnt
    return False

for i in range(maxim):
    c = 0
    if judge(i) is not False:
        print(str(judge(i)))
        c = 1
        break

if c == 0:
    print(str(maxim))