#include <cstdio>
#include <algorithm>
#define nmax 1005
using namespace std;
int n,v[nmax],s[nmax*50];
int p[nmax],k;

int main()
{
    int i,j;
    freopen("economie.in","r",stdin);
    freopen("economie.out","w",stdout);
    scanf("%d",&n);
    for (i=1;i<=n;i++)
        scanf("%d",&v[i]);
    sort(v+1,v+n+1);
    for (i=1;i<=n;i++)
        if (s[v[i]]==0) {
            s[v[i]]=1;
            p[++k]=v[i];
            for (j=v[i];j+v[i]<=v[n];j++)
                if (s[j]==1)
                    s[j+v[i]]=1;
        }
    printf("%d\n",k);
    for (i=1;i<=k;i++)
        printf("%d\n",p[i]);
    return 0;
}