{\bf 1.} ( 4 points) Illustrate the proof of Wilson's theorem for $p=19$.

{\bf 2.} (3 points) How many (circular) necklaces are there 
of length $p$, with $a$ colors? Explain!

{\bf 3.} (3 points) Use the Miller-Rabin primality test to investigage
whether the integer $15$ is prime or composite,
by picking {\bf one} random $a$'s between $2$ and $13$.