using System;

using System.Text;

​

public class Program

{

    public static string Shorten(string value)

    {

        var sb = new StringBuilder();

        int i, last;

        var isLastGroup = false;

        void Write()

        {

            var isGroup = i - last > 1;

            var getDash = last == 0 || isLastGroup ? "" : "-";

            sb.Append(isGroup ? $"{getDash}{value[last]}*{i - last}{(i != value.Length ? "-" : "")}" : value[last].ToString());

            isLastGroup = isGroup;

            last = i;

        }

​

        for (i = 0, last = 0; i < value.Length; i++)

            if (value[last] != value[i])

                Write();

        Write();

        return sb.ToString();

    }

​

    public static void Main()

    {

        Console.WriteLine(Shorten("1"));

        Console.WriteLine(Shorten("111"));

        Console.WriteLine(Shorten("1112"));

        Console.WriteLine(Shorten("1222"));

        Console.WriteLine(Shorten("12233344445555512345"));

    }

}