using System;

namespace ConsoleApplication2
{class Program
{static void Main(string[] args)
{
Recurrence x = new Recurrence { Depth = 8 };
x.Excute();
Console.ReadLine();
}}

class Recurrence{
public int Depth { get; set; }
public void Excute() { Stack(0); }
private void Stack(int value)
{
++value;
Show(value);
if (value < Depth) Stack(value);
Show(value);
}

private void Show(int value)
{
for (int i = 0; i < value; ++i)
{
Console.Write("〇");
}
Console.WriteLine();
}}}