let scan_float () = Scanf.scanf " %f" (fun x -> x)
let print_float n = Printf.printf "%.12f\n" n

let solve a b x =
  let capacity = a *. a *. b in
  if x < (capacity /. 2.0) then
    let c = x *. 2.0 /. b /. a in atan2 b c
  else
    let c = b *. 2.0 -. x *. 2.0 /. a /. a in atan2 c a

let to_degree rad = rad *. 180.0 /. (acos (-1.0))

let () =
  let a = scan_float() and b = scan_float() and x = scan_float() in
  print_float (to_degree (solve a b x)) 