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 Scala (2.11.7) (judge verdict: Accepted)

import io.StdIn._
object Main extends App {
    val n = readInt
    val as = for(_ <- 1 to n) yield readInt

    def rec(index: Int, acc: Map[Int, Int]): Map[Int, Int] = {
        if(n-1 < index) return acc
        else {
            val a = as(index)
            acc.get(a) match {
                case Some(value) =>  rec(index+1, acc.updated(a, value+1))
                case None        =>  rec(index+1, acc+(a -> 1))
            }
        }
    }

    val map = rec(0, Map.empty)
    println(map.values.count(_%2==1))
}