#include<bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<int> a(n);
for (auto& i : a) cin >> i;
int sm = accumulate(all(a), 0);
vector<uint64_t> dp(sm + 1, 0);
dp[0] = 1;
for (int i = 0; i < n; ++i) {
for (int j = sm - a[i]; j >= 0; --j) {
dp[j + a[i]] += dp[j];
}
}
if (sm & 1 || dp[sm / 2] == 0) {
cout << "0\n";
return 0;
}
vector<int> ans(sm + 1, 0);
for (int i = 1; i <= sm; ++i) ans[i] = 1;
for (int i = 0; i < n; ++i) {
for (int j = 0; j <= sm - a[i]; ++j) {
dp[j + a[i]] -= dp[j];
}
for (int k = 1; k <= sm; ++k) {
if ((sm - a[i] + k) & 1) ans[k] = 0;
int tar = (sm - a[i] + k) / 2;
if ((tar <= sm && dp[tar]) || (0 <= tar - k && tar - k <= sm && dp[tar - k])) {}
else ans[k] = 0;
}
for (int j = sm - a[i]; j >= 0; --j) {
dp[j + a[i]] += dp[j];
}
}
cout << accumulate(all(ans), 0) << '\n';
for (int i = 1; i <= sm; ++i) {
if (ans[i]) cout << i << ' ';
}
}
