#include <fstream>
#include <algorithm>
#define NMAX 1001
#define VMAX 50001
using namespace std;
ifstream fin("economie.in");
ofstream fout("economie.out");
int n,cnt,v[NMAX],c[VMAX],sol[NMAX];
int main() {
    fin>>n;
    for (int i=1;i<=n;i++)
        fin>>v[i];
    sort(v+1,v+n+1);
    for (int i=1;i<=n;i++)
        if (c[v[i]]==0) {
            sol[++cnt]=v[i];
            c[v[i]]=1;
            for (int j=1;j+v[i]<=v[n];j++)
                if (c[j]==1)
                    c[j+v[i]]=1;
        }
    fout<<cnt<<"\n";
    for (int i=1;i<=cnt;i++)
        fout<<sol[i]<<"\n";
    return 0;
}