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