#include<bits/stdc++.h>
using namespace std;
int arr[100001],b[10000];
int main(){
	int n,ans;
	int sum;
	bool flag = 1;
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> arr[i];
		for(int k=0;k<i;k++){
			if(arr[i] == arr[k]){
				flag = 0;
				ans++;
			}
		}
		if(flag){
			b[i] = arr[i];
		}
		flag = 1;
	}
	sum = n - ans;
	cout << sum << endl;
	sort(b,b+n);
	for(int i=0;i<n;i++){
		cout << b[i] << " ";
	}
	return 0;
}