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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

int main()
{
    string s; cin>>s;
    int res=s.size();
    set<char> chars(begin(s), end(s));
    if (chars.size()==1) return cout<<0<<endl, 0;

    for(auto& c: chars) {
        auto S=s;
        for(bool done=false; !done; ) {
            done=true;
            string T;
            int n=S.size();
            for(int i=0; i+1<n; ++i) {
                if (S[i]==c || S[i+1]==c)
                    T+=c;
                else {
                    T+=S[i];
                    done=false;
                }
            }
            S=T;
        }
        res=min<int>(res, s.size()-S.size());
    }
    cout<<res<<endl;
}