#include<bits/stdc++.h>
using namespace std;
int n,m,a[109],b;
int c[109];
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>b;
		if(c[b])
			continue;
		m++;
		c[b]++;
		a[m]=b;
	}
	cout<<m<<" ";
	sort(a+1,a+n+1);
	for(int i=1;i<=m;i++)
			cout<<a[i]<<" ";
	return 0;
}