#include <iostream>
#include <algorithm>
#include <vector>
#include <iterator>
#include <set>

using namespace std;

int main() {
    int n;
    cin >> n;
    if (n == 0) {
        return 0;
    }
    vector<int> v(n);
    for (int i = 0; i < n; ++i) {
        cin >> v[i];
    }
    vector<int> res;
	set<int> got;
    for (int i = n - 1; -1 < i; --i) {
        auto it = got.find(v[i])
        if (it == got.end()) {
            res.push_back(v[i]);
			got.insert(v[i]);
        }
    }
    cout << res.size() << "\n";
    for (int i = res.size() - 1; i > -1; --i) {
        cout << res[i] << " ";
    }
}