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: Time Limit Exceeded)

using System;
using System.Collections.Generic;

class Program
{
    static int n;
    static long[] a;
    static SortedList<long, int> paper; // 紙

    static void Main()
    {
        /* 入力を受け取る */
        n = int.Parse(Console.ReadLine());
        a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = long.Parse(Console.ReadLine());
        /* シミュレート */
        paper = new SortedList<long, int>();
        foreach (var ai in a)
        {
            if (!paper.ContainsKey(ai)) // 紙に書いたことがなければ
                paper.Add(ai, 1); // 1個書く
            else
            {
                if (paper[ai] == 1) // 紙に1個書いてあれば
                    paper[ai]--; // 0個に
                else // 紙に1個も書いてあれば
                    paper[ai]++; // 1個に
            }
        }
        /* 答えを計算し出力 */
        long ans = 0;
        foreach (var x in paper)
            ans += x.Value;
        Console.WriteLine(ans);
    }
}