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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

class Program {
    static void Main(string[] args) {
        int n = Cin.Ni();
        HashSet<int> list = new HashSet<int>();
        for (int i = 0; i < n; i++) {
            int a = Cin.Ni();
            if (list.Contains(a)) {
                list.Remove(a);
            } else {
                list.Add(a);
            }
        }
        Console.WriteLine(list.Count);
    }
}


public class Cin {
    private static string[] s = new string[0];
    private static int i = 0;

    private static char[] cs = new char[] { ' ' };

    public static string Next() {
        if (i < s.Length) return s[i++];
        string st = Console.ReadLine();
        while (st == "") st = Console.ReadLine();
        s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
        i = 0;
        return Next();
    }

    public static int Ni() {
        return int.Parse(Next());
    }

    public static long NextLong() {
        return long.Parse(Next());
    }

    public static double NextDouble() {
        return double.Parse(Next());
    }

}