#include<bits/stdc++.h>

using namespace std;
const int N = 110;
int a[N];

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) cin >> a[i];
    //排序，从小到大
    sort(a, a + n);
    //去重
    int cnt = unique(a, a + n) - a;

    //剩余个数
    cout << cnt << endl;
    for (int i = 0; i < cnt; i++) cout << a[i] << " ";

    return 0;
}