/*
ID: Sho10
LANG: C++
TASK:
*/
#include <bits/stdc++.h> //JuniorMonster a.k.a Sho10
#define ll long long int
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define all(a) (a).begin(), (a).end()
#define sz size
#define f first
#define s second
#define pb push_back
#define er erase
#define in insert
#define mp make_pair
#define pi pair
#define rc(s) return cout<<s,0
#define endl '\n'
#define mod 1000000007
#define PI 3.14159265359
#define CODE_START  ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n,x,s1=0,s2=0;
vector<ll>v;
vector<ll>a;
bool ciur[500005];
int32_t main(){
CODE_START;
ifstream cin("economie.in");
ofstream cout("economie.out");
cin>>n;
for(ll i=0;i<n;i++)
{
    cin>>x;
    a.pb(x);
}
sort(a.begin(),a.end());
ciur[0]=1;
for(ll i=0;i<n;i++)
if(ciur[a[i]]!){
    ciur[a[i]]=1;
    v.pb(a[i]);
    for(ll j=0;j<=5e5-a[i];j++)
    if(ciur[j]){
        ciur[j+a[i]]=1;
    }
}
cout<<v.size()<<'\n';
for(ll i=0;i<v.size();i++)
    cout<<v[i]<<'\n';
}