function crowds(double PF, double bad) {
	int delivered := 0;
	int lastSender := 0;
	int remainingRuns := 20;
	int observeSender := 0;
	int observeOther := 0;

	while(remainingRuns > 0) {
		while(delivered = 0) {
			{
				if(lastSender = 0) {
					observeSender := observeSender + 1;
				} else {
					observeOther := observeOther + 1;
				}
				lastSender := 0;
				delivered := 1;
			} [bad] {
				{
					{ lastSender:=0; } [1/5] { lastSender := 1; }
				}
				[PF]
				{
					lastSender := 0;
					// When not forwarding, the message is delivered here.
					delivered := 1;
				}
			}
		}
		// Set up new run.
		delivered := 0;
		remainingRuns := remainingRuns - 1;
	}
}