using System;
using System.IO;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		var s = "1\r\n2\r3\n4";
		var res = Regex.Matches(s, @"(?m)^\d+");
    	foreach (Match m in res)
    		Console.WriteLine(m.Value);
       
	}
}