using System;
using System.Text.RegularExpressions;
 
public class Test
{
public static void Main()
{
string str = "*1, **1, **1, ***1, *2, **2, *2, *2, **3, *3";
string result = Regex.Replace(str, @"\s*(\*\*)", "\n$1");
Console.WriteLine(result);
Console.ReadLine();
}
}