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;
    bool f = true;
    int ans = 1e9;
    for(char c = 'a';c <= 'z';c++){
        bool g = true,h = true;
        for(int i = 0;i < s.size();i++){
            if(s[i] == c)g = false;
            if(s[i] != c)h = false;
        }
        if(h){
            ans = 0;
            break;
        }
        if(g)continue;
        int k = 1;
        string t = s;
        while(k++){
            string r = "";
            for(int i = 0;i < t.size()-1;i++){
                if(t[i] == c || t[i+1] == c){
                    r += c;
                }
                else r += t[i];
            }
            t = r;
            bool f = true;
            for(int i = 0;i < t.size();i++){
                if(t[i] != c)f = false;
            }
            if(f){
                ans = min(ans,k-1);
                break;
            }
        }
    }
    cout << ans << endl;
}