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: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		Main m = new Main();
		int n = Integer.valueOf(in.readLine());
		int e;
		Node root = null;
		for(int i = 0; i < n; i++) {
			e = Integer.valueOf(in.readLine());
			if(root==null) {
				root=BSTFactory.createBinarySearchTree(m, e);
			}
			Node f = root.search(e);
			if(f==null) {
				root.insert(e);
			}else {
				f.del();
			}
		}
		System.out.println(root.count()-1);
	}
	public class Node{
		public int v;
		public Node p;
		public Node r;
		public Node l;
		public boolean isEmpty = false;
		public int layer;
		private Node(Node n) {
			p = n;
			layer = n.layer+1;
		}
		private Node(int i) {
			v = i;
			layer = 0;
		}
		public Node search(int e) {
			if(e<v) {
				if(l!=null) {
					return l.search(e);
				}else {
					return null;
				}
			}else if(v<e) {
				if(r!=null) {
					return r.search(e);
				}else {
					return null;
				}
			}else {
				return this;
			}
		}
		public Node searchMin() {
			if(l!=null) {
				return l.searchMax();
			}else {
				return this;
			}
		}
		public Node searchMax() {
			if(r!=null) {
				return r.searchMax();
			}else {
				return this;
			}
		}
		public void insert(int i) {
			if(isEmpty) {
				v=i;
				isEmpty = false;
				return;
			}
			if(i<v) {
				if(l==null) {
					l=new Node(this);
					l.v=i;
				}else {
					l.insert(i);
				}
			}else {
				if(r==null) {
					r=new Node(this);
					r.v=i;
				}else {
					r.insert(i);
				}
			}
		}
		public void del() {
			if(l==null&&r==null) {
				if(p!=null) {
					if(p.l!=null&&p.l.equals(this)) {
						p.l = null;
					}else {
						p.r = null;
					}
				}else {
					isEmpty = true;
				}
			}else if(l!=null){
				swap(l);
				l.del();
			}else if(r!=null) {
				swap(r);
				r.del();
			}else {
				Node exp=l.searchMax();
				swap(exp);
				exp = exp.l;
			}
		}
		public int count() {
			return 1 + (l!=null?l.count():0) + (r!=null?r.count():0);
		}
		private void swap(Node n) {
			n.v ^= v;
	        v ^= n.v;
	        n.v ^= v;
		}
	}
	public static class BSTFactory{
		public static Node createBinarySearchTree(Main m, int i) {
			return m.new Node(i);
		}
	}
}