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


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

        val table = Array.array (200001, 0)

        fun findAns [] = 0
          | findAns (h::tl) = 
            if Array.sub (table, h) = 1
            then
                (
                  Array.update (table, h, 0);
                  1 + findAns tl
                )
            else
                (
                  Array.update (table, h, 1);
                  findAns tl
                )

        val ans = findAns a_s
    in
        print (Int.toString ans ^ "\n")
    end