using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(DateTime.ParseExact("01/01/2021", "dd/MM/yyyy", CultureInfo.InvariantCulture));

        //Console.WriteLine(DateTime.ParseExact("jan/21", "dd/MM/yyyy", CultureInfo.InvariantCulture));

        //Console.WriteLine(DateTime.ParseExact("01/13/2021", "dd/MM/yyyy", CultureInfo.InvariantCulture));

        //Console.WriteLine(DateTime.ParseExact("40/01/2021", "dd/MM/yyyy", CultureInfo.InvariantCulture));

    }

}