The ornamental design for a watch, as shown and described.
FIG. 1 is a top view of a watch showing my new design;
FIG. 2 is a right side elevation view of the watch.
FIG. 3 is a left side elevation view of the watch.
FIG. 4 is a bottom view of the watch.
FIG. 5 is a front elevation view of the watch.
FIG. 6 is a rear elevation view of the watch; and,
FIG. 7 is a left rear perspective view of the watch with the rear cover in an opened position.
The structural elements depicted by broken lines in FIG. 7 have been shown for the purpose of illustrating portions of the watch that form no part of the claimed design.