#include <bits/stdc++.h>
#define int long long
#define vt vector
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define ff first
#define ss second
#define dbg(x) cerr << #x << " = " << x << '\n'
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vvi = vt< vt<int> >;
const int N = 1e6 + 5, mod = 1e9 + 7, inf = 1e18 + 7, B = 500, LIM = (1ll << 60);
const double eps = 1e-6;
int dp[250000];
void solve () {
int n;
cin >> n;
vt<int> a(n + 1);
int sum = 0;
for (int i = 1; i <= n; i++) cin >> a[i], sum += a[i];
if (n & 1) cout << "0\n", exit(0);
set<int> ans;
vt<int> used(N, 0);
dp[0] = 1;
for (int i = 1; i <= n; i++) {
for (int w = 500 * 500; w >= a[i]; w--) dp[w] += dp[w - a[i]];
}
for (int i = 1; i <= n; i++) {
for (int w = a[i]; w < 500 * 500; w++) dp[w] -= dp[w - a[i]];
for (int val = 1; val <= sum; val++) {
int s = sum - a[i];
s += val;
if (s & 1) continue;
if (dp[s / 2]) {
used[val]++;
if (used[val] >= n) ans.insert(val);
}
}
for (int w = 500 * 500; w >= a[i]; w--) dp[w] += dp[w - a[i]];
}
cout << sz(ans) << '\n';
for (auto x: ans) cout << x << ' ';
cout << '\n';
}
bool testcases = 0;
signed main() {
cin.tie(0) -> sync_with_stdio(0);
int test = 1;
if (testcases) cin >> test;
for (int cs = 1; cs <= test; cs++) {
solve();
}
}
