The ornamental design for a ring, as shown and described.
FIG. 1 is an elevated perspective view of a ring in accordance with the present application;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is a side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
Any broken lines, shown through in the drawing figures, are included for the purpose of illustrating environmental structures only and form no part of the claimed design.