Problem:
Score : 300 points

Problem Statement

You are playing the following game with Joisino.

Initially, you have a blank sheet of paper.

Joisino announces a number. If that number is written on the sheet, erase the number from the sheet; if not, write the number on the sheet. This process is repeated N times.

Then, you are asked a question: How many numbers are written on the sheet now?

The numbers announced by Joisino are given as A_1, ... ,A_N in the order she announces them. How many numbers will be written on the sheet at the end of the game?

Constraints

1≤N≤100000

1≤A_i≤1000000000(=10^9)

All input values are integers.

Input

Input is given from Standard Input in the following format:

N
A_1
:
A_N

Output

Print how many numbers will be written on the sheet at the end of the game.

Sample Input 1

3
6
2
6

Sample Output 1

1

The game proceeds as follows:

6 is not written on the sheet, so write 6.

2 is not written on the sheet, so write 2.

6 is written on the sheet, so erase 6.

Thus, the sheet contains only 2 in the end. The answer is 1.

Sample Input 2

4
2
5
5
2

Sample Output 2

0

It is possible that no number is written on the sheet in the end.

Sample Input 3

6
12
22
16
22
18
12

Sample Output 3

2

Solution in OCaml (4.02.3) (judge verdict: Accepted)

open Printf
open Scanf

module SI = Set.Make(
                struct
                  type t = int
                  let compare = compare
                end
              )
                    
let () =
  let n = scanf "%d " (fun x -> x) in
  let rec loop i st =
    if i = 0 then SI.cardinal st
    else
      let a = scanf "%d " (fun x -> x) in
      if SI.mem a st then loop (i-1) (SI.remove a st)
      else loop (i-1) (SI.add a st) in
  loop n SI.empty |> printf "%d\n"