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

/**************************************************************
	Problem: 1183
	User: zouliangyin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/