I claim the ornamental design for a chair, as shown.
FIG. 1 a top plan view of the chair of my design, the seat of which consists of small pads, four of which are shown separated, but able to be connected again by “hook and loop” or other appropriate fastener;
FIG. 2 is a perspective view from above the front left hand side of the chair thereof;
FIG. 3 is a bottom perspective view of the chair in an alternate configuration in which all the small pads are attached to the seat; and,