Suppose that a computer science laboratory has 15 workstations and 10 servers. A cable can be used to directly connect a workstation to a server. For each server, only one direct connection to that server can be active at any time. We want to guarantee that at any time any set of 10 or fewer workstations can simultaneously access different servers via direct connections. What is the minimum number of direct connections needed to achieve this goal? I understand the answer is 60 but I'm confused how the pigeonhole principle specifically applies. Identify where and how the pigeonhole principle applies and why at most 5 workstations per server is unacceptable.