Suppose three processer, p1, p2, and p3, are attempting to use a machine with interrupt-driven I/O concurrently. Suppose p1 has tcompute = 20 and tdevice = 50, p2 has tcompute = 30 and tdevice =10, and p3 has tcompute = 15 and tdevice = 35. Assuming that no two processes can be using any device or the CPU at the same time, what is the minimum amount of time required to execute the three processes?