#include <iostream>
#include <cstdio>
#include <algorithm>

using namespace std;

const int N = 1000 + 7;
const int S = 50000 + 7;

int n, a[N], sol[N], top;
bool ok[S];

int main()
{
    freopen ("economie.in", "r", stdin);
    freopen ("economie.out", "w", stdout);

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

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

    ok[0] = 1;

    for (int i = 1; i <= n; i++)
    {
        if (ok[a[i]] == 0)
        {
            sol[++top] = a[i];
            for (int j = 0; j + a[i] <= a[n]; j++)
            {
                if (ok[j])
                {
                    ok[j + a[i]] = 1;
                }
            }
        }
    }

    cout << top << "\n";
    for (int i = 1; i <= top; i++)
    {
        cout << sol[i] << " ";
    }
    cout << "\n";


    return 0;
}