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 Scala (2.11.7) (judge verdict: Wrong Answer)

import scala.annotation.tailrec
import scala.io.StdIn

object Main extends App {
  val S = StdIn.readLine()

  @tailrec
  def rec(str: String, currentIdx: Int = 0): Boolean = if (currentIdx + 2 >= str.length) {
    true
  } else {
    if (str.charAt(currentIdx) == str.charAt(currentIdx + 1)) {
      false
    } else {
      rec(str, currentIdx + 1)
    }
  }

  if (rec(S)) {
    println("Good")
  } else {
    println("Bad")
  }
}