The ornamental design for a cap, as shown and described.
FIG. 1 is a frontal perspective view of a cap showing our new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a right side elevation view thereof, the left side elevation view being identical thereto;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The face, head, shoulders and hair shown in broken lines are environmental subject matter included to depict how the claimed design may appear when worn and form no part of the claimed design. Broken lines shown on the cap itself are lines of stitching and form a part of the claimed design.