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 Rust (1.42.0) (judge verdict: Accepted)

use std::cmp::max;
use std::cmp::min;

fn main() {
    let s = {
        let mut buf = String::new();
        std::io::stdin().read_line(&mut buf).unwrap();
        buf = buf.trim_end().to_owned();
        buf
    };
    let mut ans = 1000;
    for i in 0..26 {
        let target: char = std::char::from_u32('a' as u32 + i).unwrap();
        let mut prev: i32 = -1;
        let mut mx = 0;
        for (i, c) in s.chars().enumerate() {
            if c == target {
                mx = max(i as i32 - prev - 1, mx);
                prev = i as i32
            }
        }
        mx = max(mx, s.len() as i32 - prev - 1);
        ans = min(mx, ans);
    }
    println!("{}", ans);
}