using System;

using System.Text.RegularExpressions;  

using System.Collections.Generic; 

using System.Linq;

public class Program

{

    public static void Main()

    {

        var text = "845-002400-342A (INST 35)";

        //string[] digits = Regex.Split(text, @"\D+");

        string[] digits = text.Replace("INST", "").Split('(', ')').Where(x => !string.IsNullOrEmpty(x)).ToArray();

​

        foreach (var d in digits)

            Console.WriteLine(d +"z");

​

    }

}