import Control.Applicative ((<$>))
import Data.Int (Int64)
import Text.Printf (printf)

main :: IO ()
main = do
    [n0, g0, v0] <- fmap read . words <$> getLine :: IO [Int64]
    let v = fromIntegral v0
    let c = (/ v) . fromIntegral . (* g0) $ div n0 5 :: Double
    printf "%.15f\n" c