import Control.Applicative import Control.Monad import Control.Monad.ST import Data.Array.ST import Data.STRef primes :: Int -> [Int] primes n = runST $ do a <- newArray (0, n) True :: ST s (STUArray s Int Bool) ps <- newSTRef [2] :: ST s (STRef s [Int]) forM_ [3, 5 .. n] $ \i -> do v <- readArray a i when v $ do modifySTRef ps (i:) forM_ [i * i, i * i + i .. n] $ \j -> writeArray a j False readSTRef ps solve n l = sum . map f $ primes ((l + 1) `div` (n - 1)) where f p = l - p * (n - 1) + 1 main = do [n, l] <- map read . words <$> getLine :: IO [Int] print $ solve n l