V = (pi)r^2 * h
where r is the radius of the end-cap and h is the height (or length) of the cylinder.
If you roll your paper along its length (which I would take as the larger of the two dimensions) then the circumference of the end-cap will be 44 cm. Thus:
C = 2(pi)r
and you can find r. The height of your cylinder would then be the other dimension of the paper, 18 cm.