sum of days

namespace ConsoleApp1
{
    using System;
    using System.Globalization;

    class Program
    {
        static void Main(string[] args)
        {
            string format = "dd-MM-yyyy";
            int counter1 = 0;
            int counter2 = 0;
            //we read the input here
            int n = int.Parse(Console.ReadLine());
            DateTime date1=DateTime.ParseExact(Console.ReadLine(),format,CultureInfo.InvariantCulture);
            DateTime date2 = DateTime.ParseExact(Console.ReadLine(), format, CultureInfo.InvariantCulture);

            for (int i = 1; i <= n; i++)
            {
                if (i % 2 == 0)
                {
                    counter1++;
                }
                else
                {
                    counter2++;
                }
            }

           int one = date1.AddDays(counter1).Day;
           int two = date2.AddDays(counter2).Day;


            Console.WriteLine(one+two);
        }
    }
}