import Data.List

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

solve a b x | a*a*b < 2*x = (atan (2 * (a*a*b - x) / (a ** 3))) / pi * 180
            | otherwise = (atan (a*b*b / (2*x))) / pi * 180