g :: Double
g = 9.8

calc :: Int -> Double
calc n = t * g where
	h = (5 * (fromIntegral n)) - 5
	t = sqrt $ (2 * h) / g 

solve :: String -> String
solve str = do
	let v = read str :: Double
	show $ head $ dropWhile (\ n -> (calc n) < v) [1..]

main :: IO ()
main = interact (unlines . (map solve) . lines)