We can define the distance between two points in ways other than euclidean. In the plane, the L_m-distance between points p₁ and p₂ is given by the expression (|x₁ − x₂|^m + |y₁ − y₂|^m)^1/m. Euclidean distance, therefore, is L₂-distance. Modify the closest-pair algorithm to use the L₁-distance, which is also known as the Manhattan distance.