using System.Globalization;
public static void Main()
string s = "2020-12-03 13:26";
DateTime SelectedDate = DateTime.ParseExact(s, "yyyy-MM-dd HH:mm", CultureInfo.InvariantCulture);
Console.WriteLine(SelectedDate);
Console.WriteLine(CultureInfo.InvariantCulture.Calendar.GetWeekOfYear(SelectedDate,CalendarWeekRule.FirstDay,System.DayOfWeek.Sunday));
Console.WriteLine(SelectedDate.Year);
Console.WriteLine((int) SelectedDate.DayOfWeek);
Console.WriteLine(SelectedDate.AddDays(1 - ((int) SelectedDate.DayOfWeek)-1));
Console.WriteLine(SelectedDate.AddDays(7 - ((int) SelectedDate.DayOfWeek)-1));
Console.WriteLine(SelectedDate.AddDays(1 - ((int) SelectedDate.DayOfWeek)-1).ToShortDateString() + " - " + SelectedDate.AddDays(7 - ((int) SelectedDate.DayOfWeek)-1).ToShortDateString());