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: Runtime Error)

#include<stdio.h>
#include<stdbool.h>
#include<string.h>

bool all(char *str) {
    int i = 0;
    bool a = true;
    if(str[0] == '\0') {
        return false;
    }
    while(str[i+1] != '\0') {
        if(str[i] != str[i+1]) {
            a = false;
            break;
        }
        i++;
    }
    return a;
}

int main(void) {
    int i;
    int j;
    int memo;
    int result = 100;
    char str1[100];
    char str[100];
    scanf("%s", str1);
    char a = 'a';
    for(i = 0; i <= 'z'-'a'; i++) {
        strcpy(str, str1);
        memo = 0;
        while(true) {
            j = 0;
            while(true) {
                if(str[j+1] == '\0') {
                    str[j] = '\0';
                    break;
                }
                if(str[j] == a || str[j+1] == a) {
                    str[j] = a;
                }
                j++;
            }
            printf("%s\n", str);
            memo++;
            if(all(str)) {
                break;
            }
        }
        printf("%d\n", memo);
        if(memo < result) {
            result = memo;
        }
        a++;
    }
    printf("%d\n", result);
    return 0;
}