using System;
using System.Text.RegularExpressions;

namespace regextest
{
    class Program
    {
        static void Main(string[] args)
        {
            string input = "a;b; ;c;;;d";
            string[] values = Regex.Split(input, @";+");
            foreach (var value in values)
                Console.WriteLine(value);
        }
    }
}