#include <fstream>
#include <algorithm>

using namespace std;

ifstream in("economie.in");
ofstream out("economie.out");
int n, m;
int v[1005];
int frec[50005];
int ans[1005];

int main()
{
    in>>n;

    for(int i = 1; i<=n; i++)
    {
        in>>v[i];
    }

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

    for(int i = 1; i<=n; i++)
    {
        if(frec[v[i]] == 0)
        {
            frec[v[i]] = 1;
            m++;
            ans[m] = v[i];
        }

        for(int j = 1; j+v[i] <= 50000; j++)
        {
            frec[j + v[i]] = 1;
        }
    }

    out<<m<<'\n';
    for(int i = 1; i<=m; i++)
    {
        out<<ans[i]<<'\n';
    }

    return 0;
}