Applicant claims the ornamental design for a sofa, as shown and described.
FIG. 1 is a front perspective view of a sofa of Applicant's design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a first side elevational view thereof, the second side elevational view opposite the first side elevational view and being a mirror image thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The broken lines illustrate portions of the sofa that form no part of the claimed design.
The appearance of any portion of the sofa between one set of the break lines or between the other set of the break lines forms no part of the claimed design.