using System;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
        string pattern = @"([^\s,]+),\s*([^\s,]+(?:, CPA, CFA)?)$";
        string input = "John, Jan, Joe\nJohn, Jan, Joe, CPA, CFA\njake, jan, joe, john, jessie, jack, jones";
		Console.WriteLine(Regex.Replace(input, pattern, @"$1 and $2", RegexOptions.Multiline));
	}
}