Advanced Topics 4. Difference between Dates

// Write a program that enters two dates in format dd.MM.yyyy and returns the number of days between them.

namespace _04.DifferenceBetweenDates
{
    using System;
    using System.Globalization;
    using System.Threading;

    public class DifferenceBetweenDates
    {
        public static void Main(string[] args)
        {
            checked
            {
                Console.WriteLine("The Date must enters exactly like this format [dd.MM.yyyy] !");
                Console.Write("Enter the First date: ");
                DateTime firstDate = ReadStringFromInputAndConvertToDateTimeFormat();
                Console.Write("Enter the Second date: ");
                DateTime secondDate = ReadStringFromInputAndConvertToDateTimeFormat();
                int daysBetweenDates = CalculateDaysBetweenTwoDates(firstDate, secondDate);
                Console.WriteLine("Days Between these two Dates are: {0} !", daysBetweenDates);
            }
        }

        private static int CalculateDaysBetweenTwoDates(DateTime firstDate, DateTime secondDate)
        {
            checked
            {
                TimeSpan diff = secondDate - firstDate;
                int days = diff.Days;
                return days;
            }
        }

        private static DateTime ReadStringFromInputAndConvertToDateTimeFormat()
        {
            checked
            {
                string inputStr = Console.ReadLine();
                string dateTimeFormatStr = "d.MM.yyyy";
                DateTime date = DateTime.ParseExact(inputStr, dateTimeFormatStr, CultureInfo.InvariantCulture);
                return date;
            }
        }
    }
}