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)

//#pragma once
#include <stdio.h>
#include <string>
#include <iostream>
#include <queue>
#include <algorithm>
#include <sstream>
#include <vector>
#include <math.h>
#include <set>
#include <map>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cctype>


using namespace std;
#define modd 1000000007


typedef pair<long long, long long> pl;


typedef string::const_iterator State;
class ParseError {};




#define ll long long




/*
class UnionFind {
public:
	vector <ll> par;
	vector <ll> siz;
	vector <ll> gr;

	// Constructor
	UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) ,gr(sz_){
		for (ll i = 0; i < sz_; ++i) par[i] = i;
	}
	void init(ll sz_) {
		par.resize(sz_);
		siz.assign(sz_, 1LL);  // resize だとなぜか初期化されなかった
		for (ll i = 0; i < sz_; ++i) par[i] = i; // 初期では親は自分自身
	}

	// Member Function
	// Find
	ll root(ll x) { // 根の検索
		while (par[x] != x) {
			x = par[x] = par[par[x]]; // x の親の親を x の親とする
		}
		return x;
	}

	// Union(Unite, Merge)
	bool merge(ll x, ll y) {
		x = root(x);
		y = root(y);
		if (x == y) return false;

		// merge technique（データ構造をマージするテク．小を大にくっつける）
		if (siz[x] < siz[y]) swap(x, y);
		siz[x] += siz[y];
		par[y] = x;
		return true;
	}



	bool issame(ll x, ll y) { // 連結判定
		return root(x) == root(y);
	}

	ll size(ll x) { // 素集合のサイズ
		return siz[root(x)];
	}


};*/


long long N, M, K, a, b, c, d, e, H, W, L;
ll A[2][100005] = {};
ll B[2][100005] = {};
ll C[200005] = {};
bool f, ff;
string S;
set <long long>sll;
pl bufpl;
vector <long long>vl[3];
vector <pl>vpl;
vector <string> vs;
set<ll> llset;

/*struct ST
{
	long long Kati;
	int bangou;

	bool operator<(const ST& another) const
	{
		return Kati < another.Kati;//比較
	};

};



vector <ST> vst;
ST st[200005];
ST bufst;
bitset<5000> bits;*/


long long modinv(long long aa, long long mm) {
	long long bb = mm, uu = 1, vv = 0;
	while (bb) {
		long long tt = aa / bb;
		aa -= tt * bb; swap(aa, bb);
		uu -= tt * vv; swap(uu, vv);
	}
	uu %= mm;
	if (uu < 0) uu += mm;
	return uu;
}



ll minn, maxx;
double ansa;
bool fl[30] = {};

string ss, sss;

int main() {


	cin >> S;
	a = 10000;
	

	for (int i = 0; i < S.size(); i++) {
		fl[S[i] - 'a'] = true;
	}

	for (int i = 0; i < 26; i++) {
		if (fl[i]) {
			ss = S;
			sss = S;
			while (true) {
				e = 0;
				for (int j = 0; j < sss.size(); ) {
					e++;
					sss = ss;

					for (int k = 0; k < sss.size() - 1; k++) {
						if (sss[k] - 'a' == i || sss[k + 1] - 'a' == i) {
							ss[k] = i + 'a';
						}
						else {
							ss[k] = sss[k];
						}
					}

					ss.pop_back();
					f = true;
					for (int k = 0; k < ss.size(); k++) {
						if (ss[k] - 'a' != i) {
							f = false;
						}
					}

					if (f) {
						if (e < a) {
							a = e;
						}
						break;
					}

					if (ss.empty()) {
						break;
					}

				}
				break;
			}

		}
	}

	b = 0;
	for (int i = 0; i < 26; i++) {
		if (fl[i]) {
			b++;
		}
	}

	if (b == 1) {
		a = 0;
	}

	cout << a << endl;

	return 0;

}