A businessman plans to locate coffee shops in a newly constructed office building. Current office tenants are located at P1 = (20.70), P2 = (30.40), P3 = (90.30), and P4 = (50.100). 50 people per day are expected to visit the first office, 30 in the second office, 70 in the third office and 60 in the last office. Seventy percent of visitors are expected to stop by the cafeteria. For each additional unit of distance traveled, the coffee shop is expected to lose $0.25 in revenue. The daily operating cost of n cafeteria is C(n) = 5000n. Determine the optimal number of cafes to build and specify their locations.