#include <vector>
#include <algorithm>
#include <fstream>

using namespace std;

ifstream cin ("elmaj.in" );
ofstream cout("elmaj.out");

vector <int> a, x;

int main()
{
    int n;
    cin >> n;
    a.resize(n);

    for (int i = 0; i < a.size(); cin >> a[i++] );

    x.push_back(a[0]);
    for (int i = 1; i < a.size(); i++)
    {
        if (x.size() != 0 && a[i] == x[x.size() - 1]) x.push_back(a[i]);
            else x.pop_back();
    }

    return 0;
}