#include<cstdio>
#include<cmath>
#include<algorithm>
#include<vector>
  
   
  
unsigned int v[100005], n,a[500005],c[100005],k;
void generare()
{
     unsigned int i;
    std::freopen("economie.in","r",stdin);
    std::scanf("%d",&n);
    for(i=1;i<=n;i++)
        std::scanf("%d",&v[i]);
    std::fclose(stdin);
           
}
void rezolvare()
{
       
    unsigned int i,q;
      
    std::sort(v+1,v+n+1);
       
    if(v[1]==1)
    {
        c[++k]=1;
        return ;
           
    }
          
     a[0]=1;
    for(i=1;i<=n;i++)
    {
        if(a[v[i]]==0)
           c[++k]=v[i];
    
    for(q=0;v[i]+q<=v[n];q++)
            if(a[q])
                a[v[i]+q]=1;
          
          
    }       
    return ;
}
void afisare()
{
    unsigned int i;
    std::freopen("economie.out","w",stdout);
    std::printf("%d\n",k);
   
       
    for(i=1;i<=k;i++)
        {
 
            std::printf("%d\n",c[i]);
 
             
    }
       
 
    std::fclose(stdout);
 
}
   
 
int main()
{
   
 
    generare();
    rezolvare();
    afisare();
    return 0;
}