The ornamental design for a scarf, as shown and described.
FIG. 1 is a perspective view showing my new scarf;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a back elevation view thereof;
FIG. 6 is a left side elevation view thereof;
FIG. 7 is a right side elevation view thereof;
FIG. 8 is a front elevation view showing how the scarf appears when worn by an individual; and,
FIG. 9 is a rear elevation view thereof.
The partial human figure shown in broken lines in the drawings is included to assist in illustrating how the scarf may appear when worn. The features of the scarf shown in broken lines illustrate environment. None of the subject matter shown in broken lines forms a part of the claimed design.