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 Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
    private final static Scanner sc = new Scanner(System.in);

    /**
     * joisinoお姉ちゃん達が使ってる紙です
     *
     * @author parikkus
     *
     */
    public static class Paper {
        List<Integer> writeNumber = new ArrayList<>();

        public void joisinoCall(Integer num) {
            if (writeNumber.contains(num)) {
                writeNumber.remove(num);
            } else {
                writeNumber.add(num);
            }
        }

        public int numberCount() {
            return writeNumber.size();
        }
    }

    /**
     * 本処理を実行します。
     */
    public static void execute() {
        int n = nextInt();
        Paper p = new Paper();

        for (int i = 0; i < n; i++) {
            p.joisinoCall(nextInt());
        }

        out(p.numberCount());
    }

    /**
     * 次の標準入力をintで受け取ります。
     * @return 標準入力値(int)
     */
    public static int nextInt() {
        return sc.nextInt();
    }

    /**
     * 次の標準入力をStringで受け取ります。
     * @return 標準入力値(String)
     */
    public static String nextString() {
        return sc.next();
    }

    /**
     * 次の標準入力を指定回数分intで受け取ります。
     * @param n 取得回数
     * @return 取得した標準入力値の配列(int)
     */
    public static int[] nextInts(int n) {
        int[] arr = new int[n];

        for (int i = 0; i < n; i++) {
            arr[i] = nextInt();
        }

        return arr;
    }

    /**
     * 標準出力にオブジェクトを出力します。
     * @param o 出力対象
     */
    public static void out(Object o) {
        System.out.println(o);
    }

    public static void main(String[] args) {
        execute();
    }
}