/*#include<iostream> using namespace std; int main(){ int n,k; cin>>n>>k; int a[n+1]; for(int i=1;i<n+1;i++) cin>>a[i]; for(int i=k;i>0;i--){ cout<<a[i]<<" "; } for(int i=k+1;i<=n;i++) cout<<a[i]<<" "; return 0; } */ #include<iostream> using namespace std; int main(){ int n,tmp,ans; int cnt[1001]={}; while(n--){ cin>>tmp; cnt[tmp]++; if(cnt[tmp]==1) ans++; } cout<<ans<<endl; int i=1; while(cnt[i]==0) i++; cout<<i; for(i=1;i<1001;i++){ if(cnt[i]>0) cout<<" "<<i; } return 0; }