The ornamental design for a desk, as shown and described.
FIG. 1 is a perspective view of a desk.
FIG. 2 is a front elevation view thereof.
FIG. 3 is a rear elevation view thereof.
FIG. 4 is a right side elevation view thereof. A left side elevation view is a mirror image of the right side elevation view.
FIG. 5 is a top plan view thereof.
FIG. 6 is a bottom plan view thereof.
FIG. 7 is a cross-sectional view taken along the line 7-7 in FIG. 2.
FIG. 8 is a cross-sectional view taken along the line 8-8 in FIG. 2; and,
FIG. 9 is a perspective view of the desk shown in an alternate position.
The broken lines shown in the drawings are included for the purpose of illustrating unclaimed portions of the desk, and form no part of the claimed design.