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 <string.h>

int max(int a, int b) {
	if (a > b) return a;
	else return b;
}

int min(int a, int b) {
	if (a > b) return b;
	else return a;
}

int main(void) {
	char s[101] = { 0 };
	int len, i, j, sp, x, ans, pre_ans;
	int *eq;

	scanf("%s", &s);
	len = strlen(s);
	eq = (int*)malloc(sizeof(int)*len);
	for (i = 0; i < len; i++) eq[i] = 0;

	ans = len;
	for (i = 0; i < len; i++) {
		if (eq[i] == 0) {
			x = i;
			j = i + 1;
			pre_ans = i;
			while (j < len) {
				if (s[x] == s[j]) {
					sp = j - x - 1;
					x = j;
					eq[j] = 1;
					pre_ans = max(sp, pre_ans);
				}
				else if (j == len - 1) {
					pre_ans = max(pre_ans, len - x - 1);
				}
				j++;
			}
			ans = min(ans, pre_ans);
		}
	}

	printf("%d\n", ans);
	
	return 0;
}