The ornamental design for a bench, as shown and described.
FIG. 1 is a perspective view of a bench showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a side elevational view, the opposite side being a mirror image thereof; and,
FIG. 4 is a top view thereof.
The views of the bench not shown form no part of the claimed design. The broken lines depicting a tunic, leg lacings, stretcher bars, and nail heads represent environmental elements only and form no part of the claimed design.