#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,i,m=0,j,k,h=0,l=0,a[101]={0};
	cin>>n;
	for(i=1;i<=n;i++){
		cin>>j;//20
		for(k=1;k<=i;k++){
			if(a[k]==j){
				break;	
				}
			if(a[k]==0){
				a[k]=j;
				h++;
				break;
			}
				
		}
	}
	for(l=h-1;l>0;l--){
		for(i=1;i<=l;i++){
			if(a[i+1]<a[i]){
				swap(a[i+1],a[i]);
		}
	}
}
	cout<<h<<endl;
	for(i=1;i<=h;i++){
		cout<<a[i]<<endl;
	}

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