using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(TryParseIt("4/25/18 3:11 PM", out var d1));

        Console.WriteLine(d1.ToString("o"));

        Console.WriteLine(TryParseIt("04/25/18 3:11 PM", out var d2));

        Console.WriteLine(d2.ToString("o"));

        Console.WriteLine(TryParseIt("04/25/18 10:11 PM", out var d3));

        Console.WriteLine(d3.ToString("o"));

        Console.WriteLine(TryParseIt("04/2/18 10:11 PM", out var d4));

        Console.WriteLine(d4.ToString("o"));

    }

    public static bool TryParseIt(string input, out DateTime theDate)

    {

        return DateTime.TryParseExact(input, "M/d/yy h:mm tt", CultureInfo.InvariantCulture, DateTimeStyles.None, out theDate);

    }

}