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\ufeffAmazon uses small, Roombashaped robots, called "Drives". They deliver large stacks of products to human workers by following set paths around the warehouse.
The warehouse can be represented in the form of a cartesian plane, where robots are located at integral points of the form x \ufeffy \ufeffWhen a product is to be delivered to some point i \ufeffj \ufeffthe nearest robot is sought and chosen. Thus if a robot is surrounded by other robots nearby, it will seldom be chosen for work. More formally, a robot is said to be idle if it has a robot located above, below, left, and right of it \ufeffIt is guaranteed that no two robots are at the same location.
Given the locations of n robots, find the number of idle robots.
Example
The x and y coordinates are given as two arrays, with the coordinates aligned by index: x
and y
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