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 Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program name
    use,intrinsic :: iso_fortran_env
    implicit none
    character(100):: s
    integer(int32):: ans,i,si,osi,dst,inf=1000000000

    read*, s
    ans=inf
    do i=ichar('a'),ichar('z')
        ! print*, '--',char(i)
        dst=0
        osi=0
        do si=1,len_trim(s)
            if (s(si:si) == char(i)) then
                dst=max(dst,si-osi-1)
                osi=si
            end if
        end do
        ! print*, dst,len_trim(s)-osi-1
        dst=max(dst,len_trim(s)-osi)
        osi=inf
        do si=1,len_trim(s)
            if (s(si:si)==char(i)) then
                osi=si
                exit
            end if
        end do
        ! print*, osi-1,dst
        ans=min(ans, max(osi-1,dst))
    end do
    print'(i0)', ans
end program name