#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int N = 5e2 + 5;
const int NN = 500*500 + 5;
#define pb push_back
#define sz size()
#define ff first
#define ss second
vector <int> v, jog;
int n, a[N], dp[NN], san[NN], sum;
map <int, bool> m[NN];
int main () {
// freopen("input.txt", "r", stdin);
// freopen ("cykar.txt", "w", stdout);
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
sum += a[i];
}
// for (int i = 1; i <= n; ++i) {
// cout << a[i] << " ";
// }
// return 0;
dp[0] = 1;
for (int i = 1; i <= n; ++i) {
for (int j = sum - a[i]; j >= 0; j--) {
if (dp[j]) {
dp[j + a[i]] = 1;
m[j + a[i]][a[i]] = 1;
for (auto jj : m[j]) {
m[j + a[i]][jj.ff] = 1;
}
}
}
}
if (sum % 2 == 1 or !dp[sum / 2]) {
cout << "0\n";
return 0;
}
for (int i = 0; i <= sum; ++i) {
if (dp[i]) {
v.pb (i);
}
}
for (int i = 1; i <= n; ++i) {
map <int, bool> mp;
for (int j : v) {
// j we sum - j
int grup1 = j;
int grup2 = sum - j;
if (m[grup1].find(a[i]) != m[grup1].end()) {
int sum1 = grup1 - a[i];
int variant = abs(sum1 - grup2);
if (mp.find (variant) == mp.end()) {
san[variant]++;
mp[variant] = 1;
}
}
}
}
for (int i = 0; i <= sum; ++i) {
if (san[i] == n) {
jog.pb (i);
}
}
cout << (int)jog.sz << "\n";
for (int i : jog) {
cout << i << " ";
}
}
