{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE BangPatterns #-}

import Control.Applicative
import Control.Monad
import Control.Arrow
import Data.List
import Data.Maybe
import Data.Char
import qualified Data.ByteString.Char8 as B
import Text.Printf
import Debug.Trace

import Control.Monad.ST
import Data.Array.ST

eratosthenes n = runST $ do
	isPrime <- newArray ( 0, n ) True :: ST s ( STUArray s Integer Bool )
	writeArray isPrime 0 False
	writeArray isPrime 1 False
	forM_ [ 2 .. n ] $ \i -> do
		f <- readArray isPrime i
		when f $ do
			forM_ [ j | j <- [ 2 .. n ], i * j <= n ] $ \j ->
				writeArray isPrime ( i * j ) False
	filterM ( readArray isPrime ) [ 0 .. n ]

readInt = ( readLn :: IO Int )
readInts = map ( fst . fromJust . B.readInt ) . B.words <$> B.getLine
readNInts = readInt >>= flip replicateM readInt

which a b f = if f then a else b
mp [ a, b ] = ( a, b )

main = readLn >>= print . sum . eratosthenes