#include<bits/stdc++.h>
using namespace std;
long long num,n,a[105],cnt[105],b[105];
int main(){
	cin>>n;
	for(int i = 1;i <= n;i++){
		cin>>a[i];
		cnt[a[i]]++;
		if(cnt[a[i]] < 2){
			num++;
			b[i] = a[i];
		}
	}
	sort(b+1,b+n+1);
	cout<<num<<"\n";
	for(int i = 1;i <= n;i++){
		if(b[i] != 0){
			cout<<b[i]<<" ";
		}
	}
	return 0;
}