using System;

​

public class Program

{

    public static void Main()

    {

        int n1, num;

        Console.WriteLine("enter number");

        num = int.Parse(Console.ReadLine());

        n1 = num;

        while (num != 0 && num >= n1)

        {

            n1 = num;

            num = int.Parse(Console.ReadLine());

        }

​

        if (num == 0)

            Console.WriteLine("good");

        else

            Console.WriteLine("error");

    }

}