sicily 1341

//while(1)
//{
//cin >> n;
//}
//和
//while(cin >> n)
//{
//}
//的区别很重要，时间有很大的差距！
#include "iostream"
#include "set"
using namespace std;
int main()
{
	int N;
	while (cin >> N)
	{
		set<int> s;
		set<int>::iterator it;
		int *a = new int[N];
		for (int i = 0; i < N; i++)
		{
			cin >> a[i];
			s.insert(a[i]);
		}
		int size = s.size();
		cout << size << endl;
		bool isFirst = true;//通过这个来判断空格的输出
		for (it = s.begin(); it != s.end(); it++)
		{
			if(!isFirst)
				cout << " ";
			cout << *it;
			isFirst = false;
		}
		cout << endl;
	}
}