There are two points in the plane, so we can draw two segments between the original and each of them respectively. Calculate the angle between the two segments. \includegraphics{https://static.e-olymp.com/content/49/49270e28ebc371c9e6e548fe5edf6353526f0ecb.jpg} The angel should be a radian and less than (\textbf{3.1415926}…). Be careful, it's angle, not the cute angel. \InputFile The first line contains a single integer \textbf{T}, indicating the number of test cases. Each test case begins contains four integers \textbf{X_a}, \textbf{Y_a}, \textbf{X_b}, \textbf{Y_b} (\textbf{-10000} ≤ \textbf{X_a}, \textbf{X_b}, \textbf{Y_a}, \textbf{Y_b} ≤ \textbf{10000}), indicating the coordinates of the two points. You can assume both of them won't be the original point. \OutputFile For each case, output the angle rounded to three fractional digits.