#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("economie.in");
ofstream fout("economie.out");
int n,v[1001],i,s[50001],k,d,x,sol[1001],j;
int main()
{
    fin>>n;
    k=0;
    for(i=1;i<=n;i++)
        fin>>v[i];
    sort(v+1,v+n+1);
    s[0]=1;
    for(i=1;i<=n;i++)
        if(s[v[i]]==0){
            sol[++k]=v[i];
            x=v[i];
            d=v[n]-x;
            for(j=0;j<=d;j++)
                if(s[j]==1)
                    s[j+x]=1;
        }
    fout<<k<<'\n';
    for(i=1;i<=k;i++)
        fout<<sol[i]<<" ";
    return 0;
}