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Compute the Cross-Ratio
Given four points A, B, C and D on a line, with coordinates a < b < c < d, their cross ratio is defined as: ((c-a)*(d-b))/((c-b)*(d-a)).
Input
four different integer values in any order
Output
The cross ratio: ((c-a)*(d-b))/((c-b)*(d-a)).
Example
10,18,12,19 -->...