Let $S$ be a set, that is, a collection of objects.
We say that an object $x$ is an element of $S$ if $x$ is a member of this collection.
We write $x\in S$ when $x$ is an element of $S$ (not to be confused with the Greek letter $\epsilon$ (epsilon)),
and $x\not\in S$ when $x$ is not an element of $S$.
For which of the following sets $S$ is the word "Seven'' NOT an element of $S$, that is, Seven $\not\in S$: