#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int n, v[1001], marked[50001];
vector<int> sol;

int main() {
    freopen("economie.in", "r", stdin);
    freopen("economie.out", "w", stdout);
    
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> v[i];
    }
    sort(v, v+n);
    
    for (int i = 0; i < n; ++i) {
        if (!marked[v[i]]) {
            marked[v[i]] = 1;
            sol.push_back(v[i]);
            for (int k = 1; k < v[n-1]; ++k) {
                if (marked[k]) {
                    marked[k + v[i]] = 1;
                }
            }
        }
    }
    
    cout << sol.size() << "\n";
    for (auto it : sol) {
        cout << it << "\n";
    }
    
    return 0;
}