-- Generates the sequence of prime numbers.
-- Based on http://qiita.com/little_Haskeller/items/614a3ae20a517c19bb1f
primes :: Integral a => [a]
primes = map fromIntegral primes'
    where
        primes' = [2, 3, 5] ++ sieve2 5 7 (drop 2 primes')
        sieve2 m s (p : ps) = [n | n <- ns, gcd m n == 1] ++ sieve2 (m * p) (p * p) ps
            where ns = [x + y | x <- [s, s + 6 .. p * p - 2], y <- [0, 4]]

numOfPrimes :: Int -> Int
numOfPrimes 1 = 0
numOfPrimes n = length $ takeWhile (<= n) primes

main :: IO ()
main = putStr . unlines . map show . map numOfPrimes . map read . lines =<< getContents