huge-gcd.hs

import Data.Functor

readInt = read <$> getLine :: IO Int
readIntArray = map read . words <$> getLine :: IO [Int]

m = 10^9 + 7

mm a b = (a * b) `mod` m

extractCD2 :: (Int, [Int]) -> Int -> (Int, [Int])
extractCD2 (acd, bs) a = case result of (cd, _, bs') -> (acd `mm` cd, bs')
    where result = foldl extractCD1 (1, a, []) bs
        
extractCD1 :: (Int, Int, [Int]) -> Int -> (Int, Int, [Int])
extractCD1 (acd, a, bs') b = (acd `mm` cd, a `div` cd, (b `div` cd):bs')
    where cd = gcd a b

solve :: [Int] -> [Int] -> Int
solve as bs = fst . foldl extractCD2 (1, bs) $ as

main = do
  n <- readInt
  as <- readIntArray
  m <- readInt
  bs <- readIntArray
  print $ solve as bs