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: Wrong Answer)

#include<iostream>
#include<string>


using namespace std;

int main(){
  string str;
  cin >> str;
  int count[21]={0};

  int ans[21] = {0};
 
  for(int j = 0; j < 21;j++){
    int t = -1,now = 0;
    for(int i = 0;i < str.length();i++){
      if(str[i] == 'a' + j){
	now = i;
	if(ans[j] < now - t){
	  ans[j] = now - t - 1;
	  cout << ans[j] << endl;
	  t = now;
	}
	
      }
    }
    if(ans[j] < str.length() - t - 1){
      ans[j] = str.length() - t - 1;
    }
  }
  int min = 999;
  for(int i = 0;i < 21;i++){
    if(ans[i] != 0 && min > ans[i]) min = ans[i];
  }
  int f = 1;
  for(int i = 0; i < str.length() - 1;i++){
    if(str[i] != str[i+1]) f = 0;
  }
  if(f == 0)cout << min;
  else cout << "0";
  
}