#include <cstdio>
#include <algorithm>

using namespace std;
int i,aux,n,b,k,j,p,v[1100],m,s,a[1100],maxi,x;
int frec[50100];

int main()
{
    freopen ("economie.in","r",stdin);
    freopen ("economie.out","w",stdout);

    scanf("%d",&n);
    maxi=0;
    for(i=1;i<=n;i++)
    {
        scanf("%d",&v[i]);
    }
    sort(v+1,v+n+1);
    maxi=v[n];
    int nr=0,cont=0;
    for(i=1;i<=n;i++)
    {
        if(frec[v[i]]==0)
        {
            //printf("ok");
            nr++;
            //printf("%d ",v[i]);
            a[nr]=v[i];
            x=v[i];
            frec[v[i]] = 1;
            for(j=0;j<=v[n]-v[i];j++){
                if(frec[j]==1){frec[j+a[i]]=1;}
            }
        }
    }
    printf("%d\n",nr);
    for(i=1;i<=nr;i++)
    {
        printf("%d ",a[i]);
    }
}