Scanf.scanf "%f %f %f %f" (fun a b x y ->

    let x1 = min x (y *. a /. b) in
    let y2 = min y (x *. b /. a) in

    let y1 = x1 *. b /. a in
    let x2 = y1 *. a /. b in

    Printf.printf "%.8f\n" @@ max (x1 +. y1) (x2 +. y2)
)