I claim the ornamental design for a cap, as shown and described.
FIG. 1 is a rear perspective view of a cap showing my new design;
FIG. 2 is a front elevation view of the cap illustrated in FIG. 1;
FIG. 3 is a rear elevation view of the cap illustrated in FIG. 1;
FIG. 4 is a first side elevation view of the cap illustrated in FIG. 1;
FIG. 5 is a second side elevation view of the cap illustrated in FIG. 1;
FIG. 6 is a top plan view of the cap illustrated in FIG. 1; and,
FIG. 7 is a bottom plan view of the cap illustrated in FIG. 1.
The broken lines depicting the buckle and the broken lines along the crown are included for the purpose of illustrating environmental subject matter and form no part of the claimed design.