A Fido store stocks iPhone 15. The average demand for iPhone 15 is 10 units per day with a standard deviation of 0.5 units. Fido Corporate office has a VMI agreement with the stores and monitors the stores' stock every 15 days to figure out how much to replenish. The lead time to receive any order is 7 days. To maintain a 99% service level for iPhone 15, how much safety stock does the store need? (Provide an answer in whole units.)