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


fun findAns [] cards = List.hd cards
  | findAns (h::tl) cards = 
    let
        val taked = List.take (cards, h)
        val dropped = List.drop (cards, h)

        val nextTop = List.hd (List.rev taked)
        val nextFirstHalf = List.rev (List.tl (List.rev taked))
    in
        findAns tl (nextTop :: (nextFirstHalf @ dropped))
    end
    

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

        val initialCards = List.tabulate (n, fn i => i + 1)
        val ans = findAns a_s initialCards
    in
        print (Int.toString ans ^ "\n")
    end