#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define sz(a) (int)((a).size())
#define all(a) (a).begin(), (a).end()
#define lsb(x) (x & (-x))
#define vi vector<int>
#define YES { cout << "YES" << endl; return; }
#define NO { cout << "NO" << endl; return; }
using ll = long long;
using pii = std::pair<int, int>;
const int NMAX = 5e2;
const int GMAX = 8e5;
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int s;
struct Knapsack {
int dp[GMAX + 5];
int MOD;
Knapsack() {
MOD = rng();
dp[0] = 1;
}
void add(int x) {
for (int i = s; i >= x; --i)
dp[i] = (dp[i] + dp[i - x]) % MOD;
}
void remove(int x) {
for (int i = x; i <= s; ++i)
dp[i] = (dp[i] - dp[i - x] + MOD) % MOD;
}
};
Knapsack rucsac;
int a[NMAX + 5], n;
signed main() {
cin.tie(nullptr)->sync_with_stdio(false);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
s += a[i];
}
for (int i = 1; i <= n; ++i)
rucsac.add(a[i]);
if (s % 2 == 1 || rucsac.dp[s / 2] == 0) {
cout << "0\n";
exit(0);
}
vector<int>ans;
for (int t = 1; t <= 2 * s; ++t) {
a[n + 1] = t;
rucsac.add(a[n + 1]);
bool ok = true;
for (int i = 1; i <= n + 1 && ok; ++i) {
rucsac.remove(a[i]);
int cur_sum = s + t - a[i];
if (cur_sum % 2 != 0 || rucsac.dp[cur_sum / 2] == 0)
ok = false;
rucsac.add(a[i]);
}
if (ok)
ans.push_back(t);
rucsac.remove(a[n + 1]);
}
cout << sz(ans) << '\n';
for (auto &it : ans)
cout << it << " \n"[it == ans.back()];
return 0;
}
