import Control.Monad
import Data.List

extendedEuclidean :: Integral a => a -> a -> (a, a, a)
extendedEuclidean a 0 = (a,1,0)
extendedEuclidean a b = (d,p,q-a`div`b*p)
  where (d,q,p) = extendedEuclidean b (a`mod`b)

chineseRemainder :: Integral a => [(a,a)] -> Maybe (a,a)
chineseRemainder xs = foldl aux (Just (0,1)) xs
  where
    aux Nothing _ = Nothing
    aux (Just (b1,m1)) (b2,m2)
      | (b2-b1) `mod` d /= 0 = Nothing
      | otherwise = Just (b1+m1*(((b2-b1)*p`div`d)`mod`(m2`div`d)), m1*m2`div`d)
      where
        (d,p,q) = extendedEuclidean m1 m2

main = do
  c <- do
    chineseRemainder <$> do
      replicateM 3 $ (\[a,b] -> (a,b)) . map read . words <$> getLine :: IO [(Integer,Integer)]

  print $
    case c of
      Just (d,m) -> if d == 0 then m else d
      Nothing -> -1