using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        string dateString1 = "2/6/2018";

        string dateString2 = "20/05/2016";

        string[] formats = { "d/M/yyyy", "dd/MM/yyyy" };

        DateTime dt1 = DateTime.ParseExact(dateString1, formats, CultureInfo.InvariantCulture, DateTimeStyles.None);

        DateTime dt2 = DateTime.ParseExact(dateString2, formats, CultureInfo.InvariantCulture, DateTimeStyles.None);

        Console.WriteLine(dt1);

        Console.WriteLine(dt2);

    }

}