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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <algorithm>
using namespace std;
using ll=long long;

#include <tuple>
#include <string>
#include <vector> 
#include <set>
//https://atcoder.jp/contests/abc073/tasks/abc073_c
int cnt_digits(ll n){

    int digits =0;
    while(n > 0){

        digits++;
        n /= 10;

    }
    return digits;
}

//最大公約数
ll gcd(ll a,ll b){
    if(b ==0) return a;
    else return gcd(b ,a % b);
}

//最小公倍数
ll lcm(ll a,ll b){
  ll g = gcd(a,b);
  return (a / g) * b;
}

int main() {
    
    int n;
    cin >> n;
    set<int> a;

    for(int i=0;i <n;i++){
        bool exist = false;
        int t;
        cin >>t;
        if(i == 0){
            a.insert(t);
            continue;
        }
        
        auto p = a.find(t);
        //発見
        if(p != a.end()){
            a.erase(p);
        }else{
            a.insert(t);
        }

    }

    int ans = a.size();

    cout << ans << endl;
    
    return 0;
}