#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <unordered_set>
#include <cstdlib>
#include <cstring>
#include <string>
#include <set>
#include <map>
#include <algorithm>
#include <bitset>
#include <queue>
#include <unordered_map>
#include <fstream>
#include <random>
typedef unsigned long long ull;
typedef long long ll;
using namespace std;
const int N = 510;
const int M = 500010;
int a[N];
bitset <M> b[N];
bool ch[N][2 * M];
int main() {
int n, sm = 0;
cin >> n;
bitset <M> w;
w[0] = 1;
for (int i = 1; i <= n; i++) {
cin >> a[i];
if (a[i] % 2 != a[1] % 2) {
cout << "0\n";
return 0;
}
w |= (w << a[i]);
sm += a[i];
}
if (sm % 2 == 1) {
cout << "0\n";
return 0;
}
if (!w[sm / 2]) {
cout << "0\n";
return 0;
}
bitset <M> answ;
answ.set();
for (int i = 1; i <= n; i++) {
b[i][250000] = 1;
for (int j = 1; j <= n; j++) {
if (i == j) continue;
b[i] = ((b[i] << a[j]) | (b[i] >> a[j]));
}
answ &= b[i];
}
vector <int> ans;
for (int j = 250001; j <= 500000; j++) {
if (answ[j]) ans.push_back(j - 250000);
}
cout << (int)ans.size() << "\n";
for (auto it : ans) {
cout << it << " ";
}
cout << "\n";
}
