The CIS $1600$ TAs are feeling very bored at the start of this semester. One Sunday afternoon,

Homework $1$ CIS $16004$

Andrew, William, Shaurya, and Michael decide to have a snowball fight. Andrew and Shaurya

are on one team, and William and Michael are on another team. Shaurya is determined to win,

but Andrew is more interested in creating sets of snowballs. Andrew crafts the perfect snowball

labelled x and creates the set S$0=\{$x$\}.$ While Shaurya is fighting off attacks from William and

Michael, Andrew hypothesizes about sets S$1=$ S$0\backslash$times $\{$S$0\},$ S$2=$ S$1\backslash$times $\{$S$1\}$ and S$3=$ S$2\backslash$times $\{$S$2\}.$

Andrew gets bored of the snowball fight and proposes the following: The first TA who calculates

$|$S$0\backslash$cup S$1\backslash$cup S$2\backslash$cup S$3|$ and their corresponding teammate will win the fight. Help your favorite TAs

win the snowball fight by calculating $|$S$0\backslash$cup S$1\backslash$cup S$2\backslash$cup S$3|!$