Size of the image if the angular size of the moon = 1/2 degree?

The angular size of the moon is 1/2 degree. A typical pixel of a digital camera is 15 microns x 15 microns (where 1 micron = 10^-6 metre). If the focal length of the lens of a digital camera is 50 mm, how many pixels are contained in an image of the moon produced by this camera?