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 top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a front elevation view thereof;
FIG. 6 is a first side elevation view thereof; and,
FIG. 7 is a second side elevation view thereof.
The short dashed broken lines on the shaded claimed surface of the cap depict claimed stitching. The dot-dashed broken lines depict the bounds of the claim and form no part thereof. The broken line showing of the cap and logos illustrates the environment of the claimed design and forms no part thereof.