using System;

public class Test
{
	public static void Main()
	{
	string start = "data-token=";
      string end = " href";

      string source = "<a class='bizLink' data-token='-iUzEhgdscgbpj5VMi5zoh54FTeFt8M4mj5nsiodxR5VzZOhniodpj6nFQg0nce3MhUxFSgdxjM4JjUVzZuNu8o0sREnFSUzISUXzZWh4iodGQfdxR5VzZWh4iodGQfhli6fnce_=1\" href='";

      int firstTag = source.IndexOf(start);
      int lastTag = source.IndexOf(end, firstTag );
      int startIndex = firstTag + start.Length +1;
      int endIndex = lastTag;
      string authenticityToken = source.Substring(startIndex, endIndex - startIndex -1);
      Console.Write(authenticityToken);
	}
}