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;
using ll = long long;

int const N = 100 * 1000 + 16;
int const M = 1000 * 1000 * 1000 + 7;

int n;
string s;
char w[128];

int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);

  cin >> s;
  n = s.size();

  int ans = n;
  for(char c = 'a'; c <= 'z'; ++c) {
    int cnt = 0;
    int m = n;
    copy_n(s.begin(), n, w);
    while(1) {
      bool f = false;
      for(int i = 0; i < m; ++i)
        f |= (w[i] != c);
      if(not f)
        break;
      cnt++;
      for(int i = 0; i < m-1; ++i)
        if(w[i] != c && w[i+1] == c)
          w[i] = c;
      m--;
    }

    ans = min(ans, cnt);
  }

  cout << ans << endl;
}