Problem
A chess king is said to "attack" all squares one step away from it (basically any square right next to it in any direction), horizontally, vertically, or diagonally. For instance, a king on the center square of a grid attacks all other squares, as shown below. Suppose a white king and a black king are placed on different squares of grid so that they do not attack each other. In how many ways can this be done? [See figure in original PDF]
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