using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string data = "AB123456789C123412341234B123";

        string[] pieces = Regex.Split(data, "(?<=[a-zA-Z])|(?=[a-zA-Z])");

        foreach (string p in pieces)

            Console.WriteLine(p);

    }

}