Olivia and her three siblings bring a sack lunch to school each day, consisting of a bagel, an apple, a cookie, and a juice box. When Olivia's mom goes grocery shopping, she likes to purchase the same amount of each lunch item so that she can make complete lunches, with no leftover items. However, each item comes in a different sized package, as shown below: Bagels: six in a bag Apples: eight in a bag Cookies: twelve in a box Juice Boxes: nine in a box Find the least number of packages she must purchase in order to have the same amount of each item. Olivia's mom should purchase how many bags of apples?