#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
void addSelf(int &x, int y) {
x += y;
if (x >= mod) {
x -= mod;
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<int> a(n);
for (int &x : a) {
cin >> x;
}
int sum = accumulate(a.begin(), a.end(), 0);
vector<int> dp(sum + 1);
dp[0] = 1;
for (const int &x : a) {
for (int i = sum; i >= x; --i) {
addSelf(dp[i], dp[i - x]);
}
}
if (sum % 2 == 1 || dp[sum / 2] == 0) {
cout << "0\n";
return 0;
}
vector<bool> wt(sum + 1, true);
vector<int> newDp(sum + 1);
for (const int &x : a) {
newDp = dp;
for (int i = x; i <= sum; ++i) {
addSelf(newDp[i], mod - newDp[i - x]);
}
for (int i = 1; i <= sum; ++i) {
int newSum = sum - x + i;
if (newSum % 2 == 1 || newDp[newSum / 2] == 0) {
wt[i] = false;
}
}
}
cout << count(wt.begin() + 1, wt.end(), true) << '\n';
for (int i = 1; i <= sum; ++i) {
if (wt[i]) {
cout << i << ' ';
}
}
cout << '\n';
return 0;
}
