fun readInt () =
    valOf (TextIO.scanStream (Int.scan StringCvt.DEC) TextIO.stdIn)


fun insertionSortNoDuplicate l =
    let
        fun insert x [] = [x]
          | insert x (y::ys) = if x = y then y::ys
                               else if x < y then x::y::ys
                               else y::(insert x ys)
    in
        foldl (fn (x, acc) => insert x acc) [] l
    end


fun findAns l =
    let
        fun findAnsLoop [] min = min
          | findAnsLoop [_] min = min 
          | findAnsLoop (h1 :: h2 :: tl) min =
            if h2 - h1 < min then findAnsLoop (h2 :: tl) (h2 - h1)
            else findAnsLoop (h2 :: tl) min

        val limit = 9999999

        val ans = findAnsLoop (insertionSortNoDuplicate l) limit
    in
        if ans = limit then 0
        else ans
    end


val () =
    let
        val n = readInt ()
        val x_s = List.tabulate (n, fn _ => readInt ())
        val ans = findAns x_s
    in
        print (Int.toString ans ^ "\n")
    end