include <bits/stdc++.h>

using namespace std; int a[100001],n;; int main(){ cin>>n; for(int i = 1;i<= n;i++) cin>>a[i]; for(int i = 1;i<=n;i++) if(a[i]!=0) for(int j = i+1;j<=n;j++) if(a[j]==a[i]) a[j]=0;

for(int i = 1;i<=n;i++){
	int k=i;
	for(int j = i+1;j<=n;j++)
	    if(a[j]<a[k])
	        k=j;
	swap(a[i],a[k]);
}
int ans=0;
for(int i = 1;i<=n;i++)
	if(a[i]!=0)
	   ans++;
cout<<ans<<endl;
for(int i = 1;i<=n;i++)
    if(a[i]!=0)
        cout<<a[i]<<" ";
return 0;

}