main :: IO ()
main = do
  [a,b,x] <- map (read :: String -> Double) . words <$> getLine
  print $ ans a b x

ans :: Double -> Double -> Double -> Double
ans a b x
  | 2*x < a^2*b = atan(a*b^2/(2*x)) *180/pi
  | otherwise   = atan((2*a^2*b-2*x)/(a^3)) *180/pi