#include <bits/stdc++.h>

using namespace std;
const int N = 110;
int a[N], al;
int main() {
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];

    sort(a + 1, a + 1 + n);
    al = unique(a + 1, a + 1 + n) - a - 1;

    cout << al << endl;
    for (int i = 1; i <= al; i++) cout << a[i] << " ";
    return 0;
}