#include<iostream.h>
#include<fstream.h>
int i,j,r,t,p,aux,n,v[1001],a[50000];
int main()
{
 ifstream f("economie.in");
 ofstream g("economie.out");
 f>>n;
 for (i=1; i<n+1; i++)
  f>>v[i];
 for (i=1; i<n; i++)
  for (j=i+1; j<n+1; j++)
   if (v[i]>v[j]) { aux=v[i]; v[i]=v[j]; v[j]=aux;}
p=0;
if(v[1]==1) g<<'1'<<endl<<'1'; else
{
 for (i=v[1]; i<v[n]+1; i++)
  if(a[i]==0)
       {r=0;
       for (t=1; t<n+1; t++)
	if (v[t]==i) r=1;
       if (r==1)
       {
       a[i]=1;
       p=p+1;
	for (j=v[1]; j<v[n]+1; j++ )
	 if (a[j]!=0 && j+i<v[n]+1) a[j+i]=2;} }
 g<<p<<endl;
 for (i=v[1];i<v[n];i++)
  if(a[i]==1) g<<i<<endl;}
g.close();
return 0;
}