#include<bits/stdc++.h>
using namespace std;
int a[1001],r[50001],i,j,k,n,c[1001];
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);
    sort(a+1,a+n+1);
    for(i=1;i<=n;++i) {
        if(!r[a[i]])
            c[++k]=a[i],r[a[i]]=a[i];
        for(j=1;j<=50000-a[i];++j)
            if(r[j]&&!r[j+a[i]])
                r[j+a[i]]=j+a[i];
    }
    printf("%d\n",k);
    for(i=1;i<=k;++i)
        printf("%d\n",c[i]);
    return 0;
}