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;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using P = pair<int, int>;
ll GCD(ll a, ll b) { return b?GCD(b, a%b):a; }
ll LCM(ll a, ll b) { return a/GCD(a, b)*b; }

string s;

int main() {
    cin >> s;
    vector<int> ansalp(26, 0);
    for(int i = 0; i < 26; ++i) {
        char check = i + 'a';
        bool flg = false;
        int cnt = 0;
        for(int j = 0; j < (int)s.length(); ++j) {
            if(s.at(j) != check) {
                flg = true;
                break;
            }
        }
        if(flg) cnt++;
        string sch = s;
        while(flg) {
            string nsch;
            for(int j = 0; j < (int)(sch.length()-1); ++j) {
                if(sch.at(j) == check || sch.at(j+1) == check) {
                    nsch.push_back(check);
                }else {
                    nsch.push_back(sch.at(j));
                }
            }
            bool fflg = true;
            for(int j = 0; j < (int)nsch.length(); ++j) {
                if(nsch.at(j) != check) {
                    fflg = false;
                    break;
                }
            }
            if(fflg) {
                flg = false;
                break;
            }else {
                sch = nsch;
                cnt++;
            }
        }
        ansalp.at(i) = cnt;
    }

    sort(ansalp.begin(), ansalp.end());
    cout << ansalp.at(0) << endl;
}