#include <bits/stdc++.h>

using namespace std;

bitset<50005>ok;
vector<int> sol;
int v[1005];
int n;

int main()
{
    ifstream fin ("economie.in");
    ofstream fout ("economie.out");
    fin >> n;
    for (int i = 0; i < n; ++i){
        int x;
        fin >> x;
        v[i] = x;
    }
    ok[0] = 1;
    sort(v, v+n);
    for (int i = 0; i < n; ++i)
        if(!ok[v[i]]){
            int x = v[i];
            bool ye = false;
            for (int i = x; i <= 50000; ++i)
                if(!ok[i] && ok[i-x]){
                    ye = true;
                    ok[i] = 1;
                }
            if(ye)
                sol.push_back(x);
        }
    fout << sol.size() << "\n";
    for (vector<int>::iterator it = sol.begin(); it != sol.end(); ++it)
        fout << *it << "\n";
    fin.close();
    fout.close();
    return 0;
}