using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var strs = new List<string> { "ABC-210293CompletedReports", 
			"CC517036submittedbyfoobarforABC105799WRS877565",
			"ABC#86765",
			"abc99220 / 103743",
			"AbC99220/103743",
			"ABC 123 and 1123",
			"SubmittedbyFooBar.forABC106156.Solutionbuilton4/23/20184:22PM"
		};
    	var pattern = new Regex(@"(?i)\d{1,2}/\d{1,2}/\d{4}|(ABC.\d{1,11}| *(?:[/-]|AND) *\d{1,11})", RegexOptions.Compiled);
    	foreach (var s in strs) {
	    	var results = pattern.Matches(s)
	    		.Cast<Match>()
	    		.Select(m => m.Groups[1].Value)
	    		.ToList();
        	foreach (var t in results)
        		Console.WriteLine(t);
	}	}
}