using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var input = "12340001234567";

        var wrongInput = "12340011234567";

        Console.WriteLine(ConvertAccountIdToBban(input));

        Console.WriteLine(ConvertAccountIdToBban(wrongInput));

    }

    public static string ConvertAccountIdToBban(string input)

    {

        return Regex.Replace(input, @"^([0-9]{4})000([0-9]{7})$", "$1-$2", RegexOptions.Compiled);

    }

}