#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: chenmingyu
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/