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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Linq.Expressions;
using System.Text;

class Procon {
    static void Main (string[] agrs) {
        var S = String();

        var prev =  S[0];
        for (int i=1; i< S.Length; i++) {
          if (prev == S[i]) {
            Dbg("Bad");
            return;
          }
          prev = S[i];
        }
        Dbg("Good");
    }

    static Scanner cin = new Scanner ();
    const int M = 1000000007;
    static void Dbg (object a) => Console.WriteLine (a);
    static void Dbg (string a) => Console.WriteLine (a);
    static void Dbg<T> (IEnumerable<T> a) => Dbg (string.Join (" ", a));
    static void Dbg<T> (params object[] a) => Dbg (string.Join (" ", a));
    static void Dbgs<T> (IEnumerable<T> a) => Dbg (string.Join ("\n", a));
    static void Dbgs<T> (params object[] a) => Dbg (string.Join ("\n", a));
    static int Int () => cin.nextInt ();
    static long Long () => cin.nextLong ();
    static int[] Ints () => cin.arrayInt ();
    static long[] Longs () => cin.arrayLong ();
    static double Double () => cin.nextDouble ();
    static double[] Doubles () => cin.arrayDouble ();
    static string String () => cin.nextString ();
    static string[] Strings () => cin.arrayString ();
    static char[] Chars () => String ().ToCharArray ();
    static T Max<T> (params T[] a) => a.Max ();
    static T Min<T> (params T[] a) => a.Min ();
    static List<T> L<T> () => new List<T> ();
    static List<T> L<T> (T[] v) => new List<T> (v);
    static Dictionary<T, U> Map<T, U> () => new Dictionary<T, U> ();
    static bool Contains<T, U> (Dictionary<T, U> d, T k) => d.ContainsKey (k);
    static Dictionary<T, U>.KeyCollection Keys<T, U> (Dictionary<T, U> d) => d.Keys;
    static Dictionary<T, U>.ValueCollection Values<T, U> (Dictionary<T, U> d) => d.Values;
}

class Scanner {
    string[] s;
    int i;
    int max_i;

    public Scanner () {
        s = new string[0];
        max_i = 0;
        i = 0;
    }

    public string nextString () {
        if (i >= s.Length) {
            s = Console.ReadLine ().Split (' ');
            max_i = s.Length;
            i = 0;
            if (max_i == 0) {
                return "";
            }
            return s[i++];
        } else {
            return s[i++];
        }
    }

    public int nextInt () {
        return int.Parse (nextString ());
    }

    public long nextLong () {
        return long.Parse (nextString ());
    }

    public double nextDouble () {
        return double.Parse (nextString ());
    }

    public string[] arrayString () {
        return Console.ReadLine ().Split (' ');
    }

    public int[] arrayInt () {
        string[] str = Console.ReadLine ().Split (' ');
        int[] array = new int[str.Length];
        for (int i = 0; i < str.Length; i++) {
            array[i] = int.Parse (str[i]);
        }
        return array;
    }

    public long[] arrayLong () {
        string[] str = Console.ReadLine ().Split (' ');
        long[] array = new long[str.Length];
        for (int i = 0; i < str.Length; i++) {
            array[i] = long.Parse (str[i]);
        }
        return array;
    }

    public double[] arrayDouble () {
        string[] str = Console.ReadLine ().Split (' ');
        double[] array = new double[str.Length];
        for (int i = 0; i < str.Length; i++) {
            array[i] = double.Parse (str[i]);
        }
        return array;
    }
}