import qualified Data.ByteString.Char8 as B
import Data.Maybe
import Data.Functor

readInts :: B.ByteString -> [Int]
readInts x = fst <$> mapMaybe B.readInt (B.words x)

getParams :: B.ByteString -> (Int, Int)
getParams x = (x' !! 0, x' !! 1)
  where x' = readInts x

primes :: Int -> [Int]
primes n = sieve [2..n]
  where
    sieve (x:xs) = x : sieve ([y | y <- xs, y `mod` x /= 0])
    sieve [] = []

main =
  do
    l <- words <$> getLine
    let n = read (l !! 0) :: Int
        p = read (l !! 1) :: Double
        k = foldr (\ v r -> r + p * (fromIntegral (n `div` v - 1))) 0.0 (primes n)
    (putStrLn . show) k