#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
int n,nr,i,j,maxi,ap[50009],Q[50009],a[1009];
vector < int > v;
vector < int > :: iterator it;
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]>maxi) maxi=a[i];
}
nr=1;
Q[nr]=0;
ap[0]=1;
sort(a+1,a+n+1);
for(i=1;i<=n;i++)
{
    if(ap[a[i]]) continue;
    v.push_back(a[i]);
    for(j=1;j<=nr;j++)
        if(Q[j]+a[i]<=maxi&&ap[Q[j]+a[i]]==0)
        {
            ap[Q[j]+a[i]]=1;
            nr++;
            Q[nr]=Q[j]+a[i];
        }
}
printf("%d\n",v.size());
for(it=v.begin();it!=v.end();it++)
    printf("%d\n",*it);
return 0;
}