#include <cstdio>
#include <algorithm>
using namespace std;

int k,nr,n,i,a[1001],d[1001];
bool v[100001];
int main()
{
    freopen("economie.in", "r", stdin);
    freopen("economie.out", "w", stdout);
    scanf("%d", &n);
    for(i=1;i<=n;++i)
        scanf("%d", &a[i]);
    sort(a+1,a+n+1);
    d[++k]=a[1];
    for(i=a[1]*2;i<=a[n];i+=a[1])
        v[i]=1;
    for(i=2;i<n;++i){
        if(v[a[i]]==0){
            d[++k]=a[i];
            v[a[i]]=1;
            int nr1=nr;
            for(int t=a[1];t<=a[n]-a[i];++t)
                if(v[t]!=0&&v[t+a[i]]==0)
                    v[t+a[i]]=1;
        }
    }
    printf("%d\n", k);
    for(i=1;i<=k;++i)
        printf("%d\n",d[i]);
    return 0;
}