using System;
using System.Linq;
using System.Net.Mail;

class C { static void Main() {
	
	var input = "First, Last <email1@example.com>; First, Last <email2@example.com>;";
	
	Console.WriteLine(string.Join(",", input
		.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries)
		.Select(s => new MailAddress(s).Address)));
}}