#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MAXS = 250000 + 5;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int N;
if (!(cin >> N)) return 0;
vector<int> a(N+1);
ll S = 0;
for (int i = 1; i <= N; ++i) { cin >> a[i]; S += a[i]; }
// full dp
bitset<MAXS> dp0;
dp0.reset();
dp0[0] = 1;
for (int i = 1; i <= N; ++i) dp0 |= (dp0 << a[i]);
if ((S % 2) != 0 || !dp0[S/2]) {
cout << 0 << '\n';
return 0;
}
vector< bitset<MAXS> > pref(N+2), suf(N+2);
pref[0].reset(); pref[0][0] = 1;
for (int i = 1; i <= N; ++i) pref[i] = pref[i-1] | (pref[i-1] << a[i]);
suf[N+1].reset(); suf[N+1][0] = 1;
for (int i = N; i >= 1; --i) suf[i] = suf[i+1] | (suf[i+1] << a[i]);
vector< bitset<MAXS> > Si(N+1);
for (int i = 1; i <= N; ++i) {
Si[i].reset();
for (int q = suf[i+1]._Find_first(); q < MAXS; q = suf[i+1]._Find_next(q)) {
if (q > MAXS-1) break;
Si[i] |= (pref[i-1] << q);
}
}
unordered_map<ll,int> cnt; cnt.reserve(1000000);
auto add_candidates = [&](int i){
for (int t = Si[i]._Find_first(); t < MAXS; t = Si[i]._Find_next(t)) {
ll x1 = 2LL * t - S + a[i];
if (x1 > 0) cnt[x1]++; // positive
ll x2 = S - a[i] - 2LL * t;
if (x2 > 0) cnt[x2]++;
}
};
add_candidates(1);
for (int i = 2; i <= N; ++i) {
unordered_map<ll,int> tmp; tmp.reserve( (size_t) (cnt.size()/2 + 10) );
for (int t = Si[i]._Find_first(); t < MAXS; t = Si[i]._Find_next(t)) {
ll x1 = 2LL * t - S + a[i];
if (x1 > 0) tmp[x1] = 1;
ll x2 = S - a[i] - 2LL * t;
if (x2 > 0) tmp[x2] = 1;
}
vector<ll> to_erase;
for (auto &pr : cnt) {
if (tmp.find(pr.first) == tmp.end()) to_erase.push_back(pr.first);
}
for (ll k : to_erase) cnt.erase(k);
if (cnt.empty()) break;
}
vector<ll> ans;
ans.reserve(cnt.size());
for (auto &pr : cnt) ans.push_back(pr.first);
sort(ans.begin(), ans.end());
// output
cout << ans.size() << '\n';
if (!ans.empty()) {
for (size_t i = 0; i < ans.size(); ++i) {
if (i) cout << ' ';
cout << ans[i];
}
cout << '\n';
}
return 0;
}
