#include<stdio.h>
#include<algorithm>
using namespace std;
char c[50010];
int n,i,j,k,a[1003],nmax,nr;
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]);
                      if(a[i]>nmax) nmax=a[i];
                    }
  sort(a,a+n+1);
  if(a[1]==1){ printf("1\n1\n");
               fclose(stdin);
               fclose(stdout);
               return 0;
             }
  nr=1;  
  for(i=a[1];i<=nmax;i+=a[1])  c[i]=1;
  for(i=2;i<=n;i++)  if(!c[a[i]]) {  c[a[i]]=1;  
                                     nr++;a[nr]=a[i];
                                     for(j=2;j+a[i]<=nmax;j++) if(c[j]&&!c[j+a[i]]) c[j+a[i]]=1;
                                  }
  printf("%d\n",nr);
  for(i=1;i<=nr;i++) printf("%d\n",a[i]);
  fclose(stdin);
  fclose(stdout);
  return 0;
}