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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using static Scanner;

class Program
{
    static void Main(string[] args) {
        var writer = new StreamWriter(Console.OpenStandardOutput()) {AutoFlush = false};
        Console.SetOut(writer);
        Solve();
        Console.Out.Flush();
    }
    static void Solve() {
        var N = ScanInt();
        var set = new HashSet<int>();
        for (int i = 0; i < N; i++) {
            var num = ScanInt();
            if (set.Contains(num)) set.Remove(num);
            else set.Add(num);
        }
        Console.WriteLine(set.Count);
    }
}

public static class Scanner
{
    static readonly Stream stream = Console.OpenStandardInput();
    static readonly byte[] buffer = new byte[1024];
    static int length, p;
    static bool isEof;
    private static byte ConsoleIn() {
        if (isEof) return 0;
        if (p < length) return buffer[p++];
        p = 0;
        if ((length = stream.Read(buffer, 0, 1024)) > 0) return buffer[p++];
        isEof = true;
        return 0;
    }
    public static char GetChar() {
        var by = ConsoleIn();
        while ((by < '!' || '~' < by) && !isEof) by = ConsoleIn();
        return (char) by;
    }
    public static int ScanInt() {
        var temp = 0;
        for (var ch = GetChar(); '0' <= ch && ch <= '9'; ch = (char) ConsoleIn()) {
            temp = temp * 10 + ch - '0';
        }
        return temp;
    }
}