#include<bits/stdc++.h>
#define ll int
#define nl "\n"
#define all(v) v.begin(),v.end()
#define baraa ios_base::sync_with_stdio(false);cin.tie(NULL);
using namespace std;
const ll mod = 1e9 + 7;
ll add(ll a, ll b) {
a += b;
while (a >= mod)a -= mod;
while (a < 0)a += mod;
return a;
}
ll mul(ll a, ll b) {
return (a * b) % mod;
}
int main() {
baraa
ll n, M1 = 500 * 500 + 1, M2 = 500 * 500 / 2 + 10;
cin >> n;
vector<ll> a(n), dp(M2, 0);
vector<bool> mem(M2, 0);
ll sm = 0;
dp[0] = 1;
for (ll &i: a) {
cin >> i;
sm += i;
for (ll j = M2 - 1; j >= i; j--)
dp[j] = add(dp[j], dp[j - i]);
}
if (sm % 2 or dp[sm / 2] == 0) {
cout << 0 << nl;
return 0;
}
vector<vector<bool> > save(n);
for (ll i = 0; i < n; i++) {
for (ll j = a[i]; j < M2; j++)
dp[j] = add(dp[j], -dp[j - a[i]]);
for (ll j = 0; j < M2; j++)
mem[j] = (dp[j] > 0);
save[i] = mem;
for (ll j = M2 - 1; j >= a[i]; j--)
dp[j] = add(dp[j], dp[j - a[i]]);
}
vector<ll> ans;
for (ll x = 1; x < M1; x++) {
bool ok = 1;
for (ll i = 0; i < n and ok; i++) {
ll sm2 = (sm - a[i] + x);
ok &= (sm2 / 2 - x >= 0 and (sm2 / 2) * 2 == sm2 and save[i][min(sm2 / 2, sm2 / 2 - x)]);
}
if (ok)ans.push_back(x);
}
cout << ans.size() << nl;
for (ll i: ans) {
cout << i << ' ';
}
return 0;
}
