import Data.List (nub, sort)

allTheSame :: (Eq a) => [a] -> Bool
allTheSame xs = all (== head xs) xs

adjacentElements :: Int -> [a] -> [[a]]
adjacentElements = adjacentElements' []
    where
        adjacentElements' ys n xs@(_ : xr)
            | length xs >= n = adjacentElements' (ys ++ [take n xs]) n xr
            | otherwise      = ys

findMinimumDistance :: [Int] -> Int
findMinimumDistance xs
    | allTheSame ys = 0
    | otherwise     = minimum $ map (\(x : y : _) -> y - x) $ adjacentElements 2 ys
    where ys = sort $ nub xs

main :: IO ()
main = print . findMinimumDistance . map read . words . head . drop 1 . lines =<< getContents