#include <bits/stdc++.h>

using namespace std;

int a[1003], v[100100], n, sol[1003], k;

int main()
{
    int i, j, x;
    ifstream fin("economie.in");
    ofstream fout("economie.out");

    fin >> n;
    for (i = 1; i <= n; ++i)
        fin >> a[i];
    sort(a + 1, a + n + 1);
    v[0] = 1;
    for (i = 1; i <= n; ++i)
        if (v[a[i]] == 0)
        {
            x = a[i];
            sol[++k] = x;
            for (j = 0; j <= a[n]; j++)
                if (v[j]) v[x + j] = 1;
        }
    fout << k << "\n";
    for (i = 1; i <= k; ++i)
        fout << sol[i] << "\n";
    fin.close();
    fout.close();
    return 0;
}