List<string> pptp = new List<string>(){"ポ", "プ", "テ", "ピピック"};
Random r = new Random();

Queue<string> queue = new Queue<string>();
Queue<string> resultQueue = new Queue<string>();
	
IEnumerable<string> PPTP(Random r)
{
	while(true)
	{
		yield return pptp[r.Next(pptp.Count)];
	}
}
void Main()
{

	foreach(var elem in PPTP(r))
	{
		queue.Enqueue(elem);
		resultQueue.Enqueue(elem);
		if(queue.Count >= 4)
		{
			if(queue.Zip(pptp, (first, second) => first.Equals(second)).All(x => x))
			{
				Console.WriteLine(resultQueue);
				break;
			}
			queue.Dequeue();
		}
	}
}