#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#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); }
const int BASE = 500;
const int MX = BASE * BASE + 1;
using bts = bitset<MX>;
void solve() {
int n;
cin >> n;
vi arr(n);
forn(i, n)
cin >> arr[i];
bts s;
s[0] = 1;
int total = 0;
bool odd = true, even = true;
for(int a: arr) {
s |= s << a;
total += a;
if(a % 2)
even = false;
else
odd = false;
}
if(total % 2 || s[total / 2] == 0 || (!even && !odd))
{
cout << 0;
return;
}
vector<bool> used(501, false);
bts ans;
ans.flip();
forn(i, n) {
if(used[arr[i]]) continue;
used[arr[i]] = true;
bts w;
w[0] = 1;
forn(j, n) {
if(i == j) continue;
w |= w << arr[j];
}
int d = (total - arr[i]) / 2;
ans &= w >> d;
}
ans[0] = 0;
cout << ans.count() << '\n';
for(int i = ans._Find_first(); i < sz(ans); i = ans._Find_next(i)) {
cout << 2 * i - odd << ' ';
}
}
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();
}
}
