main = do
    [a, b, x] <- map read . words <$> getLine
    let radToDeg x = x * 180 / pi
    print $ if x <= a ^ 2 * b / 2
        then radToDeg $ atan (a * b ^ 2 / 2 / x)
        else radToDeg $ atan $ 2 * (a ^ 2 * b - x) / (a ^ 3)
