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)

def main():
    s = input()

    dic = {}
    for i in range(len(s)):
        if s[i] in dic:
            dic[s[i]].append(i)
        else:
            dic[s[i]] = [i]

    ans = 101
    for k in dic:
        dic[k].append(-1)
        dic[k].append(len(s))
        dic[k].sort()

        mx = -1
        for j in range(len(dic[k])-1):
            mx = max(mx, dic[k][j+1]-dic[k][j]-1)

        ans = min(ans, mx)

    print(ans)


if __name__ == '__main__':
    main()