using System;

using System.Threading;

using System.Threading.Tasks;

class Program

{

static async Task Main(string[] args)

    {

        var cts = new CancellationTokenSource();

        cts.CancelAfter(TimeSpan.FromSeconds(5));

​

        try

        {

            await RequestUtrnAsync(10, cts.Token).WaitAsync(cts.Token);

        }

        catch (OperationCanceledException ex)

        {

            Console.WriteLine("Operation cancelled.");

        }

        Console.ReadKey();

    }

​

    static Task RequestUtrnAsync(int secondsDelay, CancellationToken cancellationToken)

    {

        var cts = new CancellationTokenSource();

        var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, cts.Token);

        return Task.Run(() =>

        {

            var iterations = 0;

            while (iterations != secondsDelay)

            {

                iterations++;

                Console.WriteLine($"....{iterations}");

                Thread.Sleep(TimeSpan.FromSeconds(1));

            }

            linkedCts.Cancel();

            linkedCts.Token.ThrowIfCancellationRequested();

        });

    }

}