#include <fstream>
#include <algorithm>
using namespace std;
int n,i,j,t,S[5000001],v[1001],ok,nr;
int main()
{
    ifstream cin("economie.in");
    ofstream cout("economie.out");
    cin>>n;
    for(i=1;i<=n;i++)
        cin>>v[i];
    sort(v+1,v+n+1);
    for(i=1;i<=v[n];i++){
            S[v[i]]=1;
        for(j=v[i];j<=v[n];j++)
            if(S[j]!=0)
                S[j+v[i]]=1;
        ok=1;
        nr=i;
        for(t=i+1;t<=n;t++)
        if(S[t]==0){
            ok=0;
            break;
        }
        if(ok==1)
            break;
    }
    cout<<nr<<'\n';
    for(i=1;i<=nr;i++)
        cout<<v[i]<<" ";


    return 0;
}