#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;
const int mod = (1ll << 61) - 1e9 + 7;
int n, a[maxn];
bitset <maxn> ans;
bitset <maxn> tmp;
vector <int> dp(maxn , 0);
int sum = 0;
void solve()
{
cin >> n;
dp[0] = 1;
for(int i = 1; i <= n; i++)
{
cin >> a[i];
sum += a[i];
for(int j = maxn-1; j >= a[i]; j--) (dp[j] += dp[j - a[i]]) %= mod;
}
ans.reset(); ans.flip();
for(int i = 1; i <= n; i++)
{
vector <int> ndp = dp;
for(int j = a[i]; j < maxn; j++) (ndp[j] -= ndp[j - a[i]] + mod) %= mod;
tmp.reset();
for(int j = 0; 2*j <= sum - a[i] ; j++)
{
if(ndp[j] != 0) tmp[sum - a[i] - 2*j] = 1;
}
ans &= tmp;
}
cout << ans.count() << '\n';
for(int i = 0; i < maxn; i++)
{
if(ans[i]) cout << i << ' ' ;
}
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
solve();
return 0;
}
