import Control.Monad
import Control.Applicative
import Data.List
import qualified Data.Map as Map
import Data.Array
import qualified Data.ByteString.Char8 as BC
import Data.Maybe
readInts = map (fst . fromJust . BC.readInt) . BC.words <$> BC.getLine
readInt :: BC.ByteString -> Int
readInt = fst . fromJust . BC.readInt
strToInt s = (read :: String -> Int) s
    
main = do
    n <- readLn
    xsn <- map strToInt . words <$> getLine
    let xs = sort xsn
    let xn =  array (0,n-1) ([(k ,(xs!!k)) | k <- [0..(n-1)]] )
    if n==1 then print 0
            else print $ maximum [abs((xn!i)-(xn!(i+1))) | i <-[1..(n-2)]]