I am trying to find the superkeys of this relation, but I am having troubles finding out how many superkeys there are and exactly what they are. I figured out that the candidate keys were {A},{B},{C},{D}.

Here is the relation:

```
R(A,B,C,D)
Functional Dependencies:
A->B
B->C
C->D
D->A
Candidate keys: {A},{B},{C},{D} (from what I figured out)
```

Can someone please help me find the superkeys, and how exactly to find them?