using System;
using System.Text.RegularExpressions;
 
public class Test
{
	private static string Cut1(string s) 
	{
		if (s.Length <= 50)
    		return s;
 
		var firstSpaceAfterLimit = s.IndexOf(' ', 20);
 
		if (firstSpaceAfterLimit == -1)
    		firstSpaceAfterLimit = 50;
 
		if (firstSpaceAfterLimit >= 50)
    		firstSpaceAfterLimit = 50;
 
		return s.Substring(0, firstSpaceAfterLimit);
	}
 
	private static string Cut2(string s) 
	{
		return Regex.Match(s, @"^.{1,50}(?=\b|$)|^((?!\s).){50}").Value;
	}
 
	private static string Cut3(string s) 
	{
		return Regex.Match(s, @"^.{1,50}(?=\s|$)|^((?!\s).){50}").Value;
	}
 
	public static void Main()
	{
		foreach(string s in new string[] {"Just a test", "Just a test test test test test test", "Just a test test test test test test a test test test test test test", "123456789012345678901234567890123456789012345678901234567890", new String('a', 20), new string('a', 50), new string('a', 51), new string('a', 45) + ",7890123 test"})
			Console.WriteLine("s: {0}\n1: {1}\n2: {2}\n3: {3}\n", s, Cut1(s), Cut2(s), Cut3(s));
	}
}

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