#include <cstdio>
#include <algorithm>
#define DIM 50004
using namespace std;
int i,nr,ss[DIM],a[DIM],s[DIM],sw,n,j;
int solve()
{
     if(a[0]==1) {printf("1\n");printf("1");return 0;}
     for(i=0; i<n; ++i)
        {
          if(ss[a[i]]==0)
          {
                      s[++nr]=a[i];
                      ss[a[i]]=1;
                      for(j=1; j<=a[n-1]+1; ++j)
                         if(ss[j]==1&& j+a[i]<=a[n-1]+1)
                          ss[j+a[i]]=1;
          }             
                    
        }
printf("%d\n",nr);
for(i=1; i<=nr; ++i) printf("%d\n",s[i]);                
}                             
int main()
{
    freopen("economie.in","r",stdin);
    freopen("economie.out","w",stdout);
    scanf("%d",&n);
    for( i=0; i<n; ++i) scanf("%d",&a[i]);
    sort(a,a+n);
    solve();
    return 0;
}