Problem:
Score : 100 points

Problem Statement

The door of Snuke's laboratory is locked with a security code.

The security code is a 4-digit number. We say the security code is hard to enter when it contains two consecutive digits that are the same.

You are given the current security code S. If S is hard to enter, print Bad; otherwise, print Good.

Constraints

S is a 4-character string consisting of digits.

Input

Input is given from Standard Input in the following format:

S

Output

If S is hard to enter, print Bad; otherwise, print Good.

Sample Input 1

3776

Sample Output 1

Bad

The second and third digits are the same, so 3776 is hard to enter.

Sample Input 2

8080

Sample Output 2

Good

There are no two consecutive digits that are the same, so 8080 is not hard to enter.

Sample Input 3

1333

Sample Output 3

Bad

Sample Input 4

0024

Sample Output 4

Bad

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::io;
use std::str::Chars;

fn checkstr(chars:Chars) -> bool{
    let mut prenumber = None;
    for v in chars {
        match prenumber {
            Some(x) if x == v => {
                return false
            },
            _ => {},
        }
        prenumber=Some(v);
    }
    true
}

fn main() {
    let mut input= String::new();
    io::stdin().read_line(&mut input).expect("read_line err");
    let chars = input.trim().chars();
    if checkstr(chars) {
        println!("Good");
    }else{
        println!("Bad");
    }
}