import Text.Printf (printf)

binom :: Integral a => a -> a -> a
binom n k = product [n, n - 1 .. n - k + 1] `div` product [1 .. k]

solve :: (Integral a, RealFloat b) => a -> b
solve n = 12 * fromIntegral (binom n 5) / fromIntegral (binom 99 5)

main :: IO ()
main = do
    n <- readLn :: IO Int
    printf "%.12f\n" (solve n :: Double)