#include <bits/stdc++.h>
#define int long long
#define arr3 array <int , 3>
#define pii pair <int , int>
#define fi first
#define se second
#define BIT(x , k) ((x >> k)&1)
#define MASK(x) (1 << x)
using namespace std;
const int maxn = 500*500 + 10;
const int INF = 1e18;
int n, a[maxn];
bitset <maxn> ans;
bitset <maxn> dp;
void solve()
{
cin >> n;
dp.reset(); dp[0] = 1;
int sum = 0;
for(int i = 1; i <= n; i++)
{
cin >> a[i];
sum += a[i];
dp |= (dp << a[i]);
}
if(sum % 2 == 1 || dp[sum/2] == 0) {cout << 0 << '\n'; return;}
ans.reset(); ans.flip();
for(int i = 1; i <= n; i++)
{
dp.reset();
dp[0] = 1;
for(int j = 1; j <= n; j++)
{
if(i != j) dp |= (dp << a[j]);
}
bitset <maxn> tmp;
for(int j = 0; 2*j <= sum - a[i]; j++)
{
if(dp[j] && (sum - a[i] - 2*j)) tmp[sum - a[i] - 2*j] = 1;
}
ans &= tmp;
}
vector <int> print;
for(int i = 0; i < 500*500; i++)
{
if(ans[i]) print.push_back(i);
}
cout << print.size() << '\n';
for(int x: print) cout << x << ' ';
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
solve();
return 0;
}
