{- A
f :: [Char] -> String
f (x:y:ys)
    | x == y = "Bad"
    | ys == [] ="Good"
    | otherwise = f (y:ys)

main = getLine >>= putStrLn . f
-}


{- B
del :: Int -> Int -> Int -> Int
del d x y
    | d == abs x = y
    | d == abs y = x
    | otherwise = x + y

f :: [Int] -> String
f (n:l:xs) = do
    let x = [l+i-1 | i <- [1..n] ]
    let d = minimum $ map abs x
    show $ foldr1 (del d) x

main = getLine >>= putStrLn . f . map read . words
-}

{- C, TLE
f (a:b:c:d:xs) = length [x | x <- [a..b], x `mod` c /= 0 && x `mod` d /= 0 ]
-}

div2 (a,b) d 
    | a `mod` d == 0 = b `div` d - a `div` d + 1
    | otherwise      = b `div` d - a `div` d

f (a:b:c:d:xs)
    | c `mod` d == 0 = (a,b) `div2` c
    | d `mod` c == 0 = (a,b) `div2` d
    | otherwise      = b - a +1 - (a,b) `div2` c - (a,b) `div2` d + (a,b) `div2` (lcm c d)

main = getLine >>= putStrLn . show . f . map read . words
