// Make the best become better
// No room for laziness
#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 500 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n, a[maxN];
int f[maxN * maxN];
int cnt[maxN * maxN];
void ReadInput()
{
cin >> n;
for(int i=1; i<=n; i++)
cin >> a[i];
}
void Solve()
{
int sum = 0;
bool ok1 = false, ok2 = false;
for(int i=1; i<=n; i++)
{
sum += a[i];
if(a[i] & 1) ok1 = true;
else ok2 = true;
}
if(ok1 & ok2)
{
cout << 0;
return;
}
int tmp = sum;
f[0] = 1;
for(int i=1; i<=n; i++)
for(int s=tmp; s>=a[i]; s--)
f[s] += f[s - a[i]];
if(!f[sum / 2])
{
cout << 0;
return;
}
for(int i=1; i<=n; i++)
{
int cur = sum - a[i];
for(int s=a[i]; s<=tmp; s++)
f[s] -= f[s - a[i]];
for(int s=0; s<=tmp; s++)
if(f[s] && s * 2 > cur) cnt[s * 2 - cur]++;
for(int s=tmp; s>=a[i]; s--)
f[s] += f[s - a[i]];
}
vector<int> res;
for(int s=1; s<=tmp; s++)
if(cnt[s] == n) res.pb(s);
cout << res.size() << '\n';
for(int v : res)
cout << v << " ";
}
int32_t main()
{
// freopen("sol.inp", "r", stdin);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
ReadInput();
Solve();
}
