#include<bits/stdc++.h>
using namespace std;

int a[101] = {0};
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, less<int>() );
    //去重
    int n = unique(a, a + N) - a;
    //剩余个数
    cout<<n<<endl;

    for (int i = 0; i < n; i++)
    {
        cout << a[i] << " ";
    }

    return 0;
}