import Data.List

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

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