#include <bits/stdc++.h>
using namespace std;
const int VMAX = 5e4+2;
const int NMAX = 1e3+2;
int n,v[NMAX];
bitset<VMAX> dp;

ifstream fin("economie.in");
ofstream fout("economie.out");

int main()
{
    fin >> n;
    for(int i = 1; i <= n; i++){
        fin >> v[i];
    }
    sort(v+1, v+n+1);
    vector<int> ans;
    dp[0] = 1;
    for(int i = 1; i <= n; i++){
        if(dp[v[i]] == 0){
            ans.push_back(v[i]);
            int pas = 1, add = VMAX/v[i];
            while(add){
                int coef = min(add, pas);
                dp |= (dp<<(coef*v[i]));
                add -= coef;
                pas *= 2;
            }
        }
    }
    fout << ans.size() << "\n";
    for(int it: ans){
        fout << it << " ";
    }
    return 0;
}