import Data.Maybe

radToDeg :: Double -> Double
radToDeg x = x / pi * 180

trapezoid a b x
	| c >= 0    = Just $ atan $ (b - c) / a
	| otherwise = Nothing
	where c = 2 * x / a - b

triangle b x = atan $ b / a
	where a = 2 * x / b

calc' a b x = triangle b x `fromMaybe` trapezoid a b x

calc a b x = calc' a b (x / a)

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