Determine Events of a Hypothetical Sample Space

Question

This is a problem in S.Ghahramani's "Fundamentals of Probability with Stochastic Processes": At a busy international airport, arriving planes land on a first-come, first-served basis. Let $E=\text{there are at least five planes waiting to land, }$ and $F=\text{there are at most three planes waiting to land}$. Can anyone please explain how $E^{c}=\text{the event that at most four planes are waiting to land}$ and $F^{c}=\text{the event that at least four planes are waiting to land}$? What is the sample space here which leads to this conclusion?