#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
if (!(cin >> N)) return 0;
vector<int> a(N+1);
ll S = 0;
int maxa = 0;
for (int i = 1; i <= N; ++i) { cin >> a[i]; S += a[i]; maxa = max(maxa, a[i]); }
int MAXS = (int)S;
const int BSZ = 250000 + 5; // cover up to S <= 250000
if (MAXS >= BSZ) {
// safety, but per constraints this won't happen
cerr << "Sum too large\n";
return 0;
}
bitset<BSZ> full;
full.reset();
full[0] = 1;
for (int i = 1; i <= N; ++i) full |= (full << a[i]);
if ((S % 2LL) != 0 || !full[S/2]) {
cout << 0 << '\n';
return 0;
}
vector< bitset<BSZ> > pref(N+1), 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]);
int LIMIT = MAXS + maxa + 5;
vector<int> cnt(LIMIT + 1, 0);
bitset<BSZ> Si;
for (int i = 1; i <= N; ++i) {
Si.reset();
for (size_t q = suf[i+1]._Find_first(); q < (size_t)BSZ; q = suf[i+1]._Find_next(q)) {
if ((int)q > MAXS) break;
Si |= (pref[i-1] << (int)q);
}
for (size_t t = Si._Find_first(); t < (size_t)BSZ; t = Si._Find_next(t)) {
if ((int)t > MAXS) break;
ll x1 = 2LL * (ll)t - S + a[i];
if (x1 > 0 && x1 <= LIMIT) ++cnt[(int)x1];
ll x2 = S - a[i] - 2LL * (ll)t;
if (x2 > 0 && x2 <= LIMIT) ++cnt[(int)x2];
}
}
vector<int> ans;
for (int x = 1; x <= LIMIT; ++x) if (cnt[x] == N) ans.push_back(x);
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;
}
