let pi = atan 1. *. 4.
let (a, b, x) = Scanf.sscanf (read_line ()) "%f %f %f" @@ fun a b x -> (a, b, x /. a)

let s = a *. b /. 2.

let r1 = atan (2. *. x /. (a *. a))

let r2 = atan ((2. *. (a *. b -. x) /. (a *. a)))

let angle_of_rad r = r *. 180. /. pi

let () = Printf.printf "%f\n" @@ 
  if s = x then angle_of_rad @@ atan (a /. b)
  else if s > x then 90. -. angle_of_rad r1
  else angle_of_rad r2