Scanf.scanf "%d %d %d %d" (fun x1 y1 x2 y2 ->
    let rot_x cx cy x y =  y + cx - cy in
    let rot_y cx cy x y = -x + cy + cx in
    let x3 = rot_x x2 y2 x1 y1 in
    let y3 = rot_y x2 y2 x1 y1 in
    let x4 = rot_x x3 y3 x2 y2 in
    let y4 = rot_y x3 y3 x2 y2 in
    Printf.printf "%d %d %d %d\n" x3 y3 x4 y4
)