A robot is used for loading and unloading of parts to automated flexible machines. Loading time is 1 minute; unloading time is 1.5 minutes; machining time 15 minutes; Robot travel time between the machines including the inspection time is 3 minutes. Cost of robot C1=30 TL/Hour; cost of machines C2=40 TL/Hour. How many machines (integer number) should be assigned to the robot so that the total robot and machine costs per cycle are minimized