#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define pb push_back
#define all(a) a.begin(), a.end()
typedef long long ll;
typedef pair<int, int> ii;
const int N = 500 + 5;
const int mod = 1e9 + 21;
int dp[N * N];
int n, sum;
int a[N], cnt[N * N];
void fix(int &a)
{
if(a >= mod) a -= mod;
if(a < 0) a += mod;
}
void add(int x)
{
for(int i = sum; i >= x; i--)
{
dp[i] += dp[i - x];
fix(dp[i]);
}
}
void del(int x)
{
for(int i = x; i <= sum; i++)
{
dp[i] -= dp[i - x];
fix(dp[i]);
}
}
void solve()
{
cin >> n;
for(int i = 1; i <= n; i++)
cin >> a[i], sum += a[i];
if(sum & 1) cout << 0, exit(0);
int tmp = sum;
sum /= 2;
dp[0] = 1;
for(int i = 1; i <= n; i++)
add(a[i]);
if(dp[sum]== 0)
cout << 0, exit(0);
for(int i = 1; i <= n; i++)
{
del(a[i]);
tmp -= a[i];
vector<int> s;
for(int i = 0; i <= tmp / 2; i++) if(dp[i] != 0)
{
int team1 = i;
int team2 = tmp - team1;
cnt[abs(team2 - team1)]++;
}
tmp += a[i];
add(a[i]);
}
vector<int> res;
for(int i = 1; i <= 500 * 500; i++)
if(cnt[i] == n) res.pb(i);
cout << res.size() << '\n';
for(const int &x : res) cout << x << ' ';
}
signed main()
{
cin.tie(0)->sync_with_stdio(0);
int t = 1;
// cin >> t;
while(t--) solve();
return 0;
}
