#include using namespace std;

int a[10005]; int box[10005]; int main() { int n; cin >> n; for(int i = 1;i <= n;i++) { int score; cin >> score; box[score]++; } int cur = 0; for(int i = 1;i <= 10000;i++) { if(box[i] > 0) { cur++; a[cur] = i; } } cout << cur << endl; for(int i = 1;i <= cur;i++) { cout<< a[i] << " "; } return 0; }

#include<iostream>
using namespace std;
int n,a[10001],b[1001],cnt;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		if(b[a[i]]==0){
			b[a[i]]=1;
			cnt++;
		}
	}
	cout<<cnt<<endl;
	for(int i=1;i<=1000;i++){
		if(b[i])cout<<i<<" ";
	}
}

#include<bits/stdc++.h>
using namespace std;
int n,a[110],b[1010],c[110],x;
int main(){
	
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		b[a[i]]++;
	}
	for(int i=1;i<=1000;i++){
		if(b[i]){
			
		    c[x]=i;
		    x++;
	    }
	}
	sort(c,c+x);
	cout<<x<<endl;
	for(int i=0;i<x;i++){
		cout<<c[i]<<' ';
	}
	return 0;
}