-- prime numbers

import Data.List

sieve n l [] = l

sieve n l (x:u) = sieve n (x:l) (u \\ [i * x | i <- [1..(div n x)]])

primesBelow n = sieve n [] [2..n]

-- main = do (print (primesBelow 2000))

main = do (print (sum (primesBelow 4000)))

--	print (divisors 600851475143)
--	print (allPrimes !! 10000)