using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var s = "Meet me on 31/07/2019 at 3:00 PM to celebrate and then the meeting will be on 03/08/2019 at 12:00 PM.";
    		var pattern = @"(?<date>(?:(?:31([-/.])(?:0?[13578]|1[02]|(?:Jan|Mar|May|Jul|Aug|Oct|Dec)))\1|(?:(?:1|30)([-/.])(?:0?[13-9]|1[0-2]|(?:Jan|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})|(?:29([-/.])(?:0?2|Feb)\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))|(?:0?[1-9]|1\d|2[0-8])([-/.])(?:(?:0?[1-9]|(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep))|(?:1[0-2]|(?:Oct|Nov|Dec)))\4(?:(?:1[6-9]|[2-9]\d)?\d{2}))\D*(?<time>\d{1,2}:\d{2}\s[AP]M)";
    		var result = Regex.Matches(s, pattern);
		foreach (Match m in result) {
        			Console.WriteLine(m.Groups["date"].Value);
        			Console.WriteLine(m.Groups["time"].Value);
		}
	}
}

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