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 (1.15.1) (judge verdict: Accepted)

#![allow(non_snake_case)]

use std::io::{stdin, Read};
use std::str::FromStr;
fn read_option<T: FromStr>() -> Option<T> {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok()
}
fn read<T: FromStr>() -> T {
    let opt = read_option();
    opt.expect("failed to parse token")
}

fn main() {
    // 各文字の出現位置を取得
    // 最後の出現が、文字列の最後からどれくらいか
    // 各出現の間隔はどれくらいか、の最大値を使用する
    // -1と最後 + 1にその文字があると仮定して計算すると楽か
    let s: String = read();
    use std::collections::HashMap;
    let mut map: HashMap<char, Vec<usize>> = HashMap::new();
    for (i, c) in s.chars().enumerate() {
        let entry = map.entry(c).or_insert_with(|| vec![s.len()]);
        entry.push(i);
    }
    let mut ans = std::usize::MAX;
    use std::cmp::{max, min};
    for v in map.values_mut() {
        v.sort();
        let mut ans_now = v[0];
        for vec in v.windows(2) {
            let a = vec[0];
            let b = vec[1];
            ans_now = max(ans_now, b - a - 1);
        }
        ans = min(ans, ans_now);
    }
    println!("{}", ans);
}