public int getTipCount() {
		int count = 0;
		Stack<JadeNode> nodes = new Stack<JadeNode>();
		nodes.push(this);
		while (nodes.isEmpty() == false) {
			JadeNode jt = nodes.pop();
			for (int i = 0; i < jt.getChildCount(); i++) {
				nodes.push(jt.getChild(i));
			}
			if (jt.isExternal()) {
				count += 1;
			}
		}
		return count;
	}