import Data.List

main = do
  li <- getLine
  let [a,b,x] = map read $ words li
  let ans = compute a b x
  print ans

{-

       ...|
  .....   | <= a
 . t'     |
-----b----+
かなり傾くような場合
a * b * a / 2 >= x
のとき、a * b * b tan t' / 2 = x, t' = atan2 2x abb, t = pi/2-t' のとき tan t' = 1/tan t

角を超える場合
    ------+
   .      |
  .       | a
 . t'     |
-----b----+
aab - a* a* a*tan t/2 = x, tan t = 2(aab-x)/aaa
-}

compute :: Double -> Double -> Double -> Double
compute a b x
  | x == aab = 0
  | 2*x <= aab = atan2 (a*b*b) (2*x) * 180 / pi
  | True = atan2 ((aab-x)*2) (a*a*a) * 180 / pi
  where
    aab = a * a * b