Sets And Relations

Let $A=\{x: x=4 n+1, n \in Z, 0 \leq n<4\}$

$$\begin{aligned} & B=\{x: x=15 n+4, n \in N, n \leq 3\} \\ & C=\{x: x \text { is a prime number }, x \in A \cup B\} \end{aligned}$$

Then the cardinal number of set C is