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>
#include <array>
using namespace std;
using ULL = unsigned long long;
using UL = unsigned;
using LL = long long;
#define rep(i, n) for(UL i = 0; i < (n); i++)

struct Problem {

	void Solve() {
		vector<UL> ans; ans.assign(26, 0);
		vector<UL> prev; prev.assign(26, (UL)-1);
		string S; cin >> S;
		rep(i, S.size()) {
			UL p = S[i] - 'a';
			if (prev[p] == (UL)-1) {
				ans[p] = max(ans[p], i);
			}
			else {
				ans[p] = max(ans[p], (UL)(i - prev[p] - 1));
			}
			prev[p] = i;
		}
		UL ans2 = 10000000;
		rep(i, 26) {
			if (prev[i] == (UL)-1) continue;
			ans[i] = max(ans[i], (UL)(S.size() - 1 - prev[i]));
			ans2 = min(ans2, ans[i]);
		}
		cout << ans2 << endl;
	}


	Problem();
};
int main() {
	unique_ptr<Problem> p(new Problem());
	p->Solve();
	return 0;
}
Problem::Problem() {
	cout << fixed << setprecision(10);
}