Get Week Number of a Year in C#

class Program
 {
     static void Main(string[] args)
     {
         Console.WriteLine("Enter Date");
         string date = Console.ReadLine();
         DateTime inputDate = DateTime.Parse(date.Trim());
         var d = inputDate;
         CultureInfo cul = CultureInfo.CurrentCulture;

         var firstDayWeek = cul.Calendar.GetWeekOfYear(
             d,
             CalendarWeekRule.FirstDay,
             DayOfWeek.Monday);

         int weekNum = cul.Calendar.GetWeekOfYear(
             d,
             CalendarWeekRule.FirstDay,
             DayOfWeek.Monday);

         int year = weekNum == 52 && d.Month == 1 ? d.Year - 1 : d.Year;
         Console.WriteLine("Year: {0} Week: {1}", year, weekNum);
     }
 }