#include<stdio.h>
#include<algorithm>
using namespace std;

char viz[50022];

long int v[1033],sol[1033],i,j,k,l,m,n,max1;

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]);
        if(v[i]==1)
                {printf("%d\n%d",1,1);
                return 0;}
        if(v[i]>max1)max1=v[i];}

sort(v+1,v+1+n);

for(i=1;i<=n;i++)
        if(!viz[v[i]])
                {sol[++k]=v[i];
                viz[v[i]]=1;
                for(j=1;j<=max1-v[i];j++)
                           if(viz[j])viz[j+v[i]]=1;}

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

return 0;}