using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(Program.GetEmailString("aaa;ddd;fff;fffd"));

    }

     public static string GetEmailString(string emails)

        {

            if (emails == null) return string.Empty;

            var emailList = emails.Split(new string[] { ";" }, StringSplitOptions.RemoveEmptyEntries);

​

            if (emailList.Length < 1) return string.Empty;

            var count = emailList.Length - 1;

            return emailList[0] + Convert.ToString(count > 0 ? " + " + count : "");

​

​

        }

}