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 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>

char s[128];

int last[256], max[256];

int main(void) {
	int i, len,  kotae;
	if (scanf("%127s",s) != 1) return 1;

	for (i = 0; i < 256; i++) {
		last[i] = -1;
	}

	for (i = 0; i < s[i]; i++) {
		int idx = (unsigned char)s[i];
		if (i - last[idx] - 1 > max[idx]) max[idx] = i - last[idx] - 1;
		last[idx] = i;
	}

	len = i;
	for (i = 0; i < 256; i++) {
		if (len - last[i] - 1 > max[i]) max[i] = len - last[i] - 1;
	}

	kotae = len;
	for (i = 0; i < 256; i++) {
		if (max[i] < kotae) kotae = max[i];
	}

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

/*

s e r v a l
|/|/|/|/|/
s r v v l
|/|/|/|/
s v v v
|/|/|/
v v v

j a c k a l
|/|/|/|/|/
a a c a a
|/|/|/|/
a a a a

各文字は後ろへは拡散できない
ある位置の文字に統一したい → その長さになるまで待たないといけない

*/