import Control.Applicative
import Data.List
import Data.Char

getInt :: IO Integer
getInt = (\a -> read a :: Integer) <$> getLine

getIntArray :: IO [Integer]
getIntArray = ((map (\a -> read a :: Integer)) . words) <$> getLine

getStrArray :: Integer -> IO [String]
getStrArray 0 = return [] :: IO [String]
getStrArray n = (:) <$> getLine <*> (getStrArray (n - 1))

getPrime :: Integer -> [Integer]
getPrime 1 = []
getPrime 2 = [2]
getPrime n = 
    let primes = getPrime $ n - 1
    in if all (\a -> mod n a /= 0) primes then (n : primes) else primes

main = do
    print =<< ((foldr (+) 0) . getPrime) <$> getInt