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

fun intString n =
    if 0 <= n
    then Int.toString n
    else "-" ^ Int.toString (abs n)

fun quicksort [] = []
  | quicksort (h::tl) =
    let 
        val (s, b) =
            List.foldl
                (fn (x, (small, big)) =>
                    if x <= h then (x::small, big)
                    else (small, x::big))
                ([], [])
                tl
    in
        (quicksort s) @ [h] @ (quicksort b)
    end

val () =
    let
        val n = readInt ()
        val k = readInt ()
        val a_s = List.tabulate (n, fn _ => readInt ())

        val sorted_a_s = List.rev (quicksort a_s)
        val taked_a_s = List.take (sorted_a_s, k)
        val filtered_a_s = List.filter (fn a => 0 < a) taked_a_s
        val sum = List.foldl (fn (a, acc) => a + acc) 0 filtered_a_s
        
        val ans = if List.length filtered_a_s = 0 then List.hd sorted_a_s
                  else sum
    in
        print (intString ans ^ "\n")
    end