The ornamental design for a ring, as shown and described.
FIG. 1 is a perspective view of a ring viewed from the front, top, and left side;
FIG. 2 is a front view of the ring;
FIG. 3 is a rear view of the ring;
FIG. 4 is a perspective view of the ring viewed from the rear, top, and right side;
FIG. 5 is a left side view of the ring;
FIG. 6 is a right side view of the ring;
FIG. 7 is a top view of the ring; and,
FIG. 8 is a bottom view of the ring.
The broken lines show portions of the ring which form no part of the claimed design and designate a boundary between claimed and unclaimed subject matter.