The ornamental design for a cap, as shown and described.
FIG. 1 is a first perspective view of the cap of this invention;
FIG. 2 is a bottom plan view of the cap of this invention;
FIG. 3 is a top plan view of the cap of this invention;
FIG. 4 is a first side elevation view of the cap of this invention;
FIG. 5 is a second side elevation view of the cap of this invention;
FIG. 6 is a front elevation view of the cap of this invention; and,
FIG. 7 is a rear elevation view of the cap of this invention.
FIGS. 1-7, the broken lines depicting the logos, as well as the area between the broken lines of the logo, illustrate portions of the cap that form no part of the claimed design. All remaining broken lines depict claimed stitching.