#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define F first
#define S second
#define forn(i, n) for(int i = 0; i < n; ++i)
#define forbn(i, b, n) for(int i = b; i < n; ++i)
#define sz(v) (int)v.size()
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define min3(a, b, c) min(a, min(b, c))
#define lc v << 1
#define rc (v << 1) + 1
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long long ll;
typedef complex<double> cd;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
template <class T> inline void mineq(T &a, T b) { a = min(a, b); }
template <class T> inline void maxeq(T &a, T b) { a = max(a, b); }
int mod = 1000 * 1000 * 1000 + 7;
int total = 0;
vi pol2;
int add(int a, int b) {
int res = (a + b) % mod;
return res < 0 ? res + mod : res;
}
int ct[250001];
vii changes;
void divide(int d, int sh) {
changes.clear();
for(int i = total; i - d >= 0 && i - d + sh >= total / 2; i--) {
if(pol2[i] != 0) {
changes.eb(i - d, pol2[i - d]);
pol2[i - d] = add(pol2[i - d], -pol2[i]);
ct[i - d + sh] += 1;
}
}
for(ii p: changes)
pol2[p.F] = p.S;
}
void solve() {
int n;
cin >> n;
vi arr(n);
set<int> nums;
forn(i, n) {
cin >> arr[i];
nums.insert(arr[i]);
}
sort(all(arr));
bool odd = true, even = true;
for(int a: arr) {
total += a;
if(a % 2)
even = false;
else
odd = false;
}
pol2.assign(total + 1, 0);
pol2[0] = 1;
for(int a: arr) {
for(int i = total - a; i >= 0; i--) {
pol2[i + a] = add(pol2[i + a], pol2[i]);
}
}
if(total % 2 || pol2[total / 2] == 0 || (!even && !odd))
{
cout << 0;
return;
}
int tt = sz(nums);
for(int a: nums) {
int d = (a + (odd ? 1 : 0)) / 2;
divide(a, d);
}
vi vans;
int rem = (odd ? 1 : 0) + total;
forbn(i, (rem + 1) / 2, total + 1) {
if(ct[i] == tt) {
vans.pb(2 * i - rem);
}
}
cout << sz(vans) << '\n';
for(int el: vans)
cout << el << ' ';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
// freopen("triangles.in", "r", stdin);
// freopen("triangles.out", "w", stdout);
int t = 1;
// cin >> t;
while(t--) {
solve();
}
}
