#include<iostream>
#include<fstream>
#include<vector>
#include<algorithm>
using namespace std;
int a[1004],s[50005],i,n,j,sol,v[1004];
int main()
{

    ifstream cin("economie.in");
    ofstream cout("economie.out");
    cin>>n;
    for(i=1;i<=n;i++)
        cin>>a[i];
    sort(a+1,a+1+n);
    for(i=1;i<=n;i++)
    {

        if(s[a[i]]==1)
            continue;
        else
        {
            s[a[i]]=1;

            sol++;
            v[sol]=a[i];
            for(int j=a[i]+1;j<=50000;j++)
                if(s[j-a[i]]==1)
                    s[j]=1;
        }

    }
    cout<<sol<<"\n";
    for(i=1;i<=sol;i++)
        cout<<v[i]<<"\n";
    return 0;
}