#include<stdio.h>
int a[50001],s[50001],n,m,x,i,j,v[1001];
int poz(int st,int dr)
{int x=0,y=-1,aux;
 while(st<dr)
 {if(v[st]>v[dr])
  {aux=x;x=-y;y=-aux;
   aux=v[st];v[st]=v[dr];v[dr]=aux;}
  st=st+x;dr=dr+y;}
 return st;}

void sort(int st,int dr)
{if(st>=dr) return;
 int k=poz(st,dr);
 sort(st,k-1);
 sort(k+1,dr);}

int main()
{freopen("economie.in","r",stdin);
 freopen("economie.out","w",stdout);
 scanf("%d",&n);
 for(i=1;i<=n;i++) scanf("%d",&v[i]);
 sort(1,n);
 for(i=1;i<=n;i++)
 {x=v[i];
  if(a[x]) continue;
  a[x]=1;
  for(i=1;i<=50000-x;i++)  if(a[i]) a[i+x]=1;
  s[++m]=x;}
 printf("%d\n",m);
 for(i=1;i<=m;i++)
  printf("%d\n",s[i]);
 fclose(stdout);
 return 0;}