main :: IO ()
main = do
    [aw,ab] <- map read . words <$> getLine
    [bw,bb] <- map read . words <$> getLine
    [c,d] <- map read . words <$> getLine
    print $ solve aw ab bw bb c d

solve :: Int -> Int -> Int -> Int -> Int -> Int -> Int
solve aw ab bw bb 0 0 = aw
solve aw ab bw bb 0 d = if bw >= d then
                            solve (aw+d) ab (bw-d) bb 0 0
                        else
                            solve (aw+bw) ab 0 bb 0 0
solve aw ab bw bb c d = if ab >= c then
                            solve aw (ab-c) bw (bb+c) 0 d
                        else
                            solve (aw-(c-ab)) 0 (bw+(c-ab)) (bb+ab) 0 d