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>

#define REP(i, x, n) for (int i = x; i < (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x.size())
#define popcount(x) __builtin_popcount(x)
#define popcountll(x) __builtin_popcountll(x)
#define uniq(x) x.erase(unique(x.begin(), x.end()), x.end())
#define F first
#define S second
#define mp make_pair
#define eb emplace_back
#define pii pair<int, int>
#define pll pair<ll, ll>

using namespace std;

typedef long long ll;

/* --- INFやMODの値が適切か確認する --- */
// const int INF = 1 << 30;
// const ll INF = 1LL << 60;
// const ll MOD = 1000000007;

int main() {
  string t;
  cin >> t;

  int ans = 100000;

  rep(i, 26) {
    char ch = 'a' + i;
    string s = t;
    do {
      bool f = true;
      rep(j, s.size()) if (s[j] != ch) f = false;
      if (f) ans = min(ans, (int)(t.size() - s.size()));

      string tmp = "";
      rep(j, s.size() - 1) {
        if (s[j] == ch || s[j + 1] == ch)
          tmp += ch;
        else
          tmp += '-';
      }
      s = tmp;
    } while (s.size());
  }

  cout << ans << endl;
}