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)

fn main() {
    proconio::input! {
        s: proconio::marker::Chars,
    }
    let mut min_times = std::usize::MAX;
    for &c in &s {
        let mut sdash = s.clone();
        let mut count = 0;
        loop {
            if sdash.len() == 1 || sdash.windows(2).all(|x| x[0] == x[1]) {
                break;
            }
            for i in 0..sdash.len() - 1 {
                if sdash[i + 1] == c {
                    sdash[i] = sdash[i + 1];
                }
            }
            sdash.pop();
            count += 1;
        }
        min_times = std::cmp::min(min_times, count);
    }
    println!("{}", min_times);
}