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 Fortran (GNU Fortran 9.2.1) (judge verdict: Wrong Answer)

program sample
    implicit none
  
    integer(8) :: i,j,m,n,b
    integer(8),allocatable :: a(:),y(:)
  
    read(*,*) n
    allocate(a(n))
    do i=1,n
        read(*,*)a(i)
    end do
    call msort(a)
    b=0
    m=0
    do i=1,n-1
        if(a(i)==a(i+1))then
            a(i)=0
            a(i+1)=0
        
        else if(a(i)==0)then
            cycle
        else
            m=m+1
        end if
    end do
    write(*,*)m
    stop
    contains

    recursive subroutine msort(x)
    implicit none
    integer(8), intent(inout) :: x(:)
 
    integer(8) :: n, mid, i, j, k
    integer(8), allocatable :: tmp(:)
    
    n = size(x)
    
    if(n == 1) then
      return
    end if
 
    !
    ! 前半と後半に分けてソート
    ! 1~midとmid+1~nをそれぞれソート済みにする
    !
    mid = n / 2
    call msort(x(:mid))
    call msort(x(mid+1:))
 
    !
    ! tmpという配列にxを一時的に保管
    ! マージソートは外部ソート
    !
    allocate(tmp(n))
    tmp = x
 
    ! tmpの後半部分を左右反転
    do k = n, mid+1, -1
      tmp(k) = x(mid + n - k + 1)
    end do
 
    ! iは前半のリストのうちまだ見ていないものの最小値
    ! jは後半のリストのうちまだ見ていないものの最小値
    ! kは見た回数の合計
    i = 1
    j = n
 
    do k = 1, n
      !
      ! 一番左と一番右のうち小さい方をxに入れていく
      ! ここが等号つき不等号なので、安定ソートとなる
      !
      if(tmp(i) <= tmp(j)) then
        x(k) = tmp(i)
        i = i + 1
      else
        x(k) = tmp(j)
        j = j - 1
      end if
    end do
    
    deallocate(tmp)
    return
  end subroutine msort
end program sample