[填空题]
One lens of a nearsighted person’s eyqy jaxdu;7hli *b +sh* /ucr7,kl88 ktrd q/d-3kuj; (gkuuos-0l 0pb eglasses has a focal length of $-22.0 \, cm$ and the lens is 1.8 $cm$ from the eye. If the person switches to contact lenses that are placed directly on the eye, what should be the focal length of the corresponding contact lens? cm