#include<bits/stdc++.h>
using namespace std;

int a[1100],n,m;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	set<int> s(a+1,a+n+1);
	set<int>::iterator it;
	for(it=s.begin();it!=s.end();it++) m++;
	cout<<m<<endl;
	for(it=s.begin();it!=s.end();it++) cout<<*it<<" ";
	return 0;
}

/**************************************************************
	Problem: 1765
	User: admin
	Language: C++
	Result: Accepted
	Time:5 ms
	Memory:2080 kb
****************************************************************/