#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define fi first
#define se second
#define ll long long
#define ld long double
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define mpp make_pair
#define ve vector
using namespace std;
using namespace __gnu_pbds;
template<class T> using oset = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
const ll inf = 1e18; const int iinf = 1e9;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T> inline bool chmin(T& a, T b) { return (a > b ? a = b, 1 : 0); }
template <typename T> inline bool chmax(T& a, T b) { return (a < b ? a = b, 1 : 0); }
const int N = 550;
const int MX = N * N;
int a[N]; pii dp[MX + 1];
const int md1 = 1e9 + 9;
const int md2 = 998244353;
inline void add1(int &a, int b) { a += b; if (a >= md1){a -= md1;} }
inline void sub1(int &a, int b) { a -= b; if (a < 0){a += md1;} }
inline void add2(int &a, int b) { a += b; if (a >= md2){a -= md2;} }
inline void sub2(int &a, int b) { a -= b; if (a < 0){a += md2;} }
inline void add(pii &a, pii b) { add1(a.fi, b.fi), add2(a.se, b.se); }
inline void sub(pii &a, pii b) { sub1(a.fi, b.fi), sub2(a.se, b.se); }
inline void solve() {
int n;
cin >> n;
for (int i = 0; i < n; ++i) cin >> a[i];
dp[0] = {1, 1};
for (int i = 0; i < n; ++i) {
for (int j = MX - a[i]; ~j; --j) {
add(dp[a[i] + j], dp[j]);
}
}
int s = accumulate(a, a + n, 0);
if (!dp[s >> 1].fi && !dp[s >> 1].se) return void(cout << 0);
bitset<MX> res; res.set();
for (int i = 0; i < n; ++i) {
for (int j = 0; j <= MX - a[i]; ++j) {
sub(dp[a[i] + j], dp[j]);
}
bitset<MX> now;
for (int x = 0; x < MX; ++x) {
if ((s - a[i] + x) & 1) continue;
if (dp[(s - a[i] + x) >> 1].fi || dp[(s - a[i] + x) >> 1].se) now.set(x);
}
res &= now;
for (int j = MX - a[i]; ~j; --j) {
add(dp[a[i] + j], dp[j]);
}
}
int ans = res.count();
cout << ans << '\n';
int pos = res._Find_first();
for (int i = 0; i < ans; ++i) {
cout << pos << " ";
pos = res._Find_next(pos);
}
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int q = 1; // cin >> q;
while (q--) solve();
cerr << fixed << setprecision(3) << "Time execution: " << (double)clock() / CLOCKS_PER_SEC << endl;
}
