#include<stdio.h>
#include<algorithm>
using namespace std;
int i,n,v[1001],s[50001],aux,smax,j,sol[1001];
int main()
{
    freopen("economie.in","r",stdin);
    freopen("economie.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    scanf("%d",&v[i]);

    sort(v+1,v+n+1);
    for(i=0;i<=v[n];i+=v[1])
    s[i]=1;
    sol[++sol[0]]=v[1];

    for(i=2;i<=n;i++)
    {
        if(s[v[i]]==0)
        {
            sol[++sol[0]]=v[i];
            for(j=0;j<=v[n]-v[i];j++)
                if(s[j]!=0)
                s[j+v[i]]=1;
        }
    }

    printf("%d\n",sol[0]);
    for(i=1;i<=sol[0];i++)
    printf("%d\n",sol[i]);
    return 0;
}