nyoj-48

#include<iostream>
#include<fstream>
#include<algorithm>
using namespace std;
int main()
{
	int i,*a,n;
//	fstream cin("d:\\test.txt");
	cin>>n;
	a=new int[n];
	for(i=0;i<n;++i)
		cin>>a[i];
	sort(a,a+n);
	int cnt=0;
	for(i=0;i<n;++i)
		if(i+1<n && a[i]==a[i+1])
			cnt++;
	cout<<n-cnt<<endl;
	for(i=0;i<n;++i)
	{
		int j=i;
		while(i+1<n && a[i]==a[i+1])
			i++;
		cout<<a[j]<<" ";
	}
	cout<<endl;	
	delete [] a;
	return 0;
}