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 (3.8.2) (judge verdict: Accepted)

import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time, copy

sys.setrecursionlimit(10**7)
inf = 10**20
mod = 10**9 + 7

stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline().rstrip()  # ignore trailing spaces

d = []
s = ns()
que = collections.deque()
for c in s:
    if c not in d:
        d.append(c)

ans = inf
if len(d) == 1:
    print(0)
else:
    for c in d:
        t = copy.copy(s)
        for j in range(len(s) - 1):
            nt = []
            for i in range(len(t)-1):
                if c not in t[i:i+2]:
                    nt.append(t[i])
                else:
                    nt.append(c)
            if nt.count(c) == len(nt):
                ans = min(j+1, ans)
                break
            t = copy.copy(nt)
            
    print(ans)