using System;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        // Do not change this method

        try

        {

            CallService();

            Console.WriteLine("Success");

        }

        catch (Exception ex)

        {

            Console.WriteLine("Failed to call external service: " + ex);

        }

    }

    static void CallService()

    {

        CallServiceAndDisplayResult(1);

        CallServiceAndDisplayResult(0);

        CallServiceAndDisplayResult(-1);

    }

    static async void CallServiceAndDisplayResult(int integer)

    {

        var result = await ExternalService.GetStringValue(integer);

        Console.WriteLine(result);

    }

    // Do not change any code inside this class.

    // Assume this represents making a call to an external web service that we do not control.

    static class ExternalService

    {

        public static async Task<string> GetStringValue(int integer)

        {

            await Task.Delay(TimeSpan.FromSeconds(1));

            if (integer < 0)

            {

                throw new NotSupportedException("Negative integers not supported.");

            }

            return integer.ToString();

        }

    }

}