#include <bits/stdc++.h>
using namespace std;
int main(){
	int n,a[105]={0},i,s=0,b[105]={0},j,h=0,l;
	cin>>n;
	for(i=0;i<n;i++){
		cin>>a[i];
	} 
	for(i=0;i<n;i++){
		for(j=0;j<=i;j++){
			if(a[i]==b[j]){
				break;
		}else{
			if(b[j]==0){
				b[j]=a[i];
				h++;
				break;
			}
		}
		}	
	}
	for(l=h-1;l>0;l--){
		for(i=0;i<l;i++){
			if(b[i]>b[i+1]){
				swap(b[i],b[i+1]);
			}
		}
	}
	cout<<h<<endl;
	for(i=0;i<h;i++){
		cout<<b[i]<<endl;
	}	
	
	
	
}


/**************************************************************
	Problem: 1183
	User: 15159808820
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/