# include <iostream>
# include <cstdio>
# include <algorithm>
using namespace std;

int n,t;
int a[105],vis[105];

int main()
{
	freopen("random.in", "r", stdin);
	freopen("random.out", "w", stdout);
	
	scanf("%d", &n);
	t = n;
	for (int i=1;i<=n;++i)
		scanf("%d",  &a[i]);
	sort(a+1,a+n+1);
	for (int i=1;i<n;++i)
		if (a[i]==a[i+1])
		{
			vis[i+1] = 1;
			t--;
		}
	printf("%d\n", t);
	for (int i=1;i<=n;++i)
		if (!vis[i])
			printf("%d ", a[i]);
	
	return 0;
}