using System;       

​

public class Program

{

    public static void Main()

    {

        var utcNow = DateTime.UtcNow;

        DateTime? lastSuccessTime = new DateTime(2017,5,6);

        lastSuccessTime = lastSuccessTime.HasValue && lastSuccessTime < utcNow.AddDays(-2)? utcNow.AddDays(-2) : (lastSuccessTime ?? utcNow.AddDays(-1));

        // lastSuccessTime = lastSuccessTime ?? utcNow.AddDays(-1);

        // lastSuccessTime = lastSuccessTime != null ? lastSuccessTime : utcNow.AddDays(-1);

        Console.WriteLine(lastSuccessTime.HasValue.ToString());

        if(lastSuccessTime.HasValue){

            Console.WriteLine(utcNow.Date.ToString());

            Console.WriteLine(lastSuccessTime.Value.Date.ToString());

        }

    }

}