The ornamental design for a watch, as shown and described.
FIG. 1 is a top view of the invention;
FIG. 2 is a bottom view of the invention;
FIG. 3 is a side view of the invention;
FIG. 4 is a front view of the invention;
FIG. 5 is another side view of the invention, showing the side opposite that shown in FIG. 3;
FIG. 6 is a back view of the invention; and,
FIG. 7 is a perspective view of the invention.
The portions of the watch that are shown in broken lines in the drawings are for illustrative purposes only and do not form part of the claimed design.