main :: IO ()
main = do
  [a, b, x] <- map read . words <$> getLine
  let n = a * a * b
  let per = x / n
  print $ if per <= 0.5 then atan (b / (x / (b * a) * 2)) * (180 / pi)
                        else atan (((b - (x / (a * a))) * 2) / a) * (180 / pi)
