import System.IO (isEOF)

main = do
    quit <- isEOF
    if quit then return () else do
        input >>= return . solve >>= output
        main

input :: IO (Double)
input = readLn

output :: Int -> IO ()
output = print

solve :: Double -> Int
solve v_crash = max 1 (ceiling ((h_crash + 5.0)/ 5.0))
    where
    h_crash = 4.9 * t * t
    t = v_crash / 9.8