public boolean is_free(int x, int y) {
		if (needStart) {
			return true;
		}
		if (pos_x == x && pos_y == y) {
			return false;
		}
		updatePosition();
		if (pos_x == x && pos_y == y) {
			downdatePosition();
			return false;
		}
		downdatePosition();
		return true;
	}