#include "bits/stdc++.h" using namespace std; int main(){ int N,a[1001]={0},t; int count=0; scanf("%d",&N); for(int i=0;i<N;i++){ cin>>t; if(a[t]==0){ a[t]=t; count++; } } cout<<count; for(int i=0;i<1001;i++){ if(a[i]!=0) cout<<a[i]<<" "; } return 0; }