1. An input device, comprising: an obtainer comprising one or more processors configured to obtain an image output by a camera, the image capturing a hand of an object, wherein the obtainer is configured to determine a distance between a display or the camera and the object by obtaining a ratio of an area of the hand within the image relative to an area of the whole image; a display controller comprising one or more processors configured to display, in a display screen of the display, an operation screen with a size set based on the ratio obtained by the obtainer, and to display a figure in the operation screen; a determiner comprising one or more processors configured to determine an operation instruction from the object based on at least one of a motion of the object picked up by the camera and a shape of the object picked up by the camera; and wherein the display controller is configured to change the figure in synchronization with the motion of the object picked up by the camera, and the figure comprises a plurality of arrows corresponding to moving directions of the hand of the object.