let () = Scanf.scanf "%f %f\n%f %f\n%f %f\n" @@ fun x1 y1 x2 y2 x3 y3 ->
  let a = sqrt @@ (x2 -. x1) ** 2. +. (y2 -. y1) ** 2. in
  let b = sqrt @@ (x3 -. x2) ** 2. +. (y3 -. y2) ** 2. in
  let c = sqrt @@ (x1 -. x3) ** 2. +. (y1 -. y3) ** 2. in
  let s = (a +. b +. c) *. 0.5 in
  let s_ = sqrt @@ s *. (s -. a) *. (s -. b) *. (s -. c) in
  let r = s_ /. s in
  let m = max a @@ max b c in
  Printf.printf "%.13f\n" @@ m *. r /. (2. *. r +. m)
