#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 505;
const int N = 500 * 500 + 5;
const int mod[] = {998244353, 1000000009, 1000000007};
int n, a[maxn];
int f[N][3];
int cnt[N];
void solve() {
cin >> n;
int sum = 0;
f[0][0] = f[0][1] = f[0][2] = 1;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
for (int j = N - 1; j >= a[i]; --j) {
for (int md = 0; md < 2; ++md) {
f[j][md] += f[j - a[i]][md];
if (f[j][md] >= mod[md]) {
f[j][md] -= mod[md];
}
}
}
sum += a[i];
}
if (sum & 1 || (!f[sum / 2][0] and !f[sum / 2][1])) {
cout << 0;
return;
}
for (int i = 1; i <= n; ++i) {
for (int j = a[i]; j < N; ++j) {
for (int md = 0; md < 2; ++md) {
f[j][md] -= f[j - a[i]][md];
if (f[j][md] < 0) f[j][md] += mod[md];
}
}
for (int j = (sum - a[i]) / 2; j >= 0; --j) {
if (f[j][0] || f[j][1]) {
++cnt[(sum - a[i]) - j * 2];
}
}
for (int j = N - 1; j >= a[i]; --j) {
for (int md = 0; md < 2; ++md) {
f[j][md] += f[j - a[i]][md];
if (f[j][md] >= mod[md]) {
f[j][md] -= mod[md];
}
}
}
}
vector<int> res;
for (int i = 1; i < N; ++i) {
if (cnt[i] == n) res.push_back(i);
}
cout << (int)res.size() << '\n';
for (auto i : res) cout << i << " ";
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
