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)

import collections
def main():
    s = input()
    d = collections.defaultdict(list)
    chars = set(list(s))
    for c in chars:
        d[c].append(-1)
    for i in range(len(s)):
        d[s[i]].append(i)
    for c in chars:
        d[c].append(len(s))
    minmax_dist = float('inf')
    for c in chars:
        max_dist = 0
        for i in range(len(d[c])-1):
            max_dist = max(max_dist, d[c][i+1] - d[c][i]-1)
        minmax_dist = min(minmax_dist, max_dist)
    return minmax_dist


if __name__ == '__main__':
    print(main())