Java program

I need to write a program where Im walking a long the x-axis (sidewalk) which can be (-, 0) to (, 0). I have a street that will be a given constant positive width. Now as I walk a long the sidewalk I have a camera and there's a wall directly on the otherside of the street with a window with some given length (x1, streetWidth) and (x2, streetWidth). Through the window there are various objects at various random points (no object can have the same point too). I want to return how many pictures I would need to take in order to get pictures of all the random objects behind the window (lets just say two items for now). All coorindates will be whole numbers too.