FIG. 1 is a front, top, left side perspective view of the backpack, showing my new design;

FIG. 2 is a bottom, rear and left side perspective view thereof;

FIG. 3 is a front elevational thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a rear plan view thereof.

The broken lines shown in the drawings are for illustrative purposes only and form no part of the claimed design.