The ornamental design for a monitor, as shown and described.
FIG. 1 is a front perspective view of a monitor showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is a rear perspective view thereof; and,
FIG. 9 is an enlarged view of the portion encircled in FIG. 8.
The short dash-dash lines that are immediately adjacent the shaded areas and define unshaded regions represent the bounds of the claim and are not included in the claim. All other short dash-dash broken lines are directed to environment and are for illustrative purposes only. The dot-dot-dash broken lines encircling portions of the claimed design that are illustrated in enlargements form no part of the claimed design. All of the broken lines throughout the views form no part of the claimed design.