The ornamental design for a watch, as shown and described.
FIG. 1 is a front view of a watch showing my new design;
FIG. 2 is a rear view of the watch;
FIG. 3 is a top view of the watch, a bottom view being a mirror image thereof;
FIG. 4 is a left side view of the watch; and,
FIG. 5 is a right side view of the watch.
The additional broken lines showing portions of the watch are included for the purpose of illustrating portions of the article and forms no part of the claimed design.