import Control.Applicative ((<$>))
import qualified Data.ByteString.Lazy.Char8 as LC
import qualified Data.IntSet as IS
import Data.Maybe (fromJust)

unsafeReadInt :: LC.ByteString -> Int
unsafeReadInt = fst . fromJust . LC.readInt

diff :: Num a => [a] -> [a]
diff xs = zipWith (-) (tail xs) (init xs)

findMin :: [Int] -> Int
findMin xs
    | IS.size ys < 2 = 0
    | otherwise = minimum . diff . IS.toAscList $ ys
    where
        ys = IS.fromList xs

main :: IO ()
main = do
    _ <- getLine
    xs <- fmap unsafeReadInt . LC.words <$> LC.getContents
    print $ findMin xs