Assume the paper is formed by taking a pile of (printed) sheets of paper and folding it in half.
Look at the outside cover - this pairs up the first page and the last page on the outside. If there are $n$ pages altogether, the sum is $n+1$.
The other side of the same sheet has pages $2$ and $n-1$ - sum $n+1$.
In fact it is easy to see that the two pages on the same side of any of the original pieces of paper have numbers which add to $n+1$.
Here $n+1=33$ so $n=32$ - and the paper consists of $8$ folded sheets.