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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>
#include <stdlib.h>

typedef struct List {
	struct List *prev, *next;
	int id;
} list;

int main()
{
	int i, N;
	long long A[1000001];
	scanf("%d", &N);
	for (i = 1; i <= N; i++) scanf("%lld", &(A[i]));
	
	list *p, *hash[10007] = {}, data[1000001];
	long long count = 0;
	for (i = 1; i <= N; i++) {
		for (p = hash[A[i] % 10007]; p != NULL; p = p->next) {
			if (p->id == A[i]) break;
		}
		if (p == NULL) {
			data[i].prev = NULL;
			data[i].next = hash[A[i] % 10007];
			data[i].id = A[i];
			hash[A[i] % 10007] = &(data[i]);
			count++;
		} else {
			if (p->prev != NULL) p->prev->next = p->next;
			else hash[A[i]] = p->next;
			if (p->next != NULL) p->next->prev = p->prev;
			count--;
		}
	}
	
	printf("%lld\n", count);
	fflush(stdout);
	return 0;
}