The ornamental design for a countingdevice, as shown and described.
FIG. 1 is a front left perspective view of a counting device; and,
FIG. 2 is a bottom right perspective view thereof.
The counting device is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design.
The change in shading seen depicted on spherical counting elements represents a contrast in materials.