#include <bits/stdc++.h>
#include <ios>
#include <iostream>
#include <set>
#include <random>
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
#define f first
#define s second
const int MOD = 1e9+7;
const ll inf = 4*1e18;
const int mx = 5*1e5+5;
int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};
const int N = 500*500 + 5;
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n; cin >> n;
vector<int> a(n);
int odd = 0; int even = 0;
int sum = 0;
for (int i = 0; i < n; i++) {
cin >> a[i];
if (a[i] % 2) {
odd++;
} else { even++; }
sum += a[i];
}
if ((even > 0 && odd > 0) || sum%2 == 1) {
cout << 0; exit(0);
}
sort(a.begin(), a.end());
vector<bitset<N>> dp(n);
for (int i = 0; i < n; i++) {
if (i > 0 && a[i] == a[i-1]) {
dp[i] = dp[i-1];
continue;
}
dp[i].set(0);
for (int j = 0; j < n; j++) {
if (j == i) continue;
dp[i] = dp[i] | (dp[i] << a[j]);
}
}
bool og = false;
for (int i = 0; i < n; i++) {
if (dp[i][sum/2]) og = true;
}
if (!og) {
cout << 0; exit(0);
}
vector<int> ans;
for (int i = 1; i <= 500*500; i++) {
if (i%2 != a[0]%2) continue;
bool pos = true;
for (int j = 0; j < n; j++) {
int tmp = sum - a[j];
tmp += i;
tmp /= 2;
if (!(dp[j][tmp] || (i < tmp && dp[j][tmp-i]))) {
pos = false;
break;
}
}
if (pos) {
ans.push_back(i);
}
}
cout << ans.size() << "\n";
for (int i : ans) cout << i << " ";
}
