The ornamental design for a brush, as shown and described.
FIG. 1 is a perspective view of the brush showing my new design;
FIG. 2 is a further perspective view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a left view thereof;
FIG. 6 is a right view thereof;
FIG. 7 is a rear view thereof; and,
FIG. 8 is a front view thereof.
The broken lines immediately adjacent the shaded areas represent the bounds of the claimed design while all other broken lines are included for the purpose of illustrating portions of the brush; the broken lines form no part of the claimed design.