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 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>

int main(){
	char *s = (char *)malloc(sizeof(char) * 101);
	scanf("%s", s);
	int i, j, k, n, cont;
	char c;
	for(n = 0; ; n++){
		if(s[n] == '\0'){
			break;
		}
	}
	for(k = 0; ; k++){
		for(i = 0; i < 26; i++){
			c = (char)(i + (int)'a');
			cont = -1;
			for(j = 0; j - cont - 1 <= k && j < n; j++){
				if(s[j] == c){
					cont = j;
				}
			}
			if(cont >= n - k - 1){
				printf("%d\n", k);
				return 0;
			}
		}
	}
}