#include<bits/stdc++.h>
using namespace std;
#define int long long
const int mod = 2702200927022011;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int n; cin >> n;
vector<int> a(n + 1);
int sum = 0, ok = 1;
for(int i = 1; i <= n; i++){
cin >> a[i];
sum += a[i];
ok &= (a[i] % 2 == a[1] % 2);
}
vector<int> dp(sum + 1);
dp[0] = 1;
for(int i = 1; i <= n; i++){
for(int j = sum; j >= a[i]; j--) dp[j] = (dp[j] + dp[j - a[i]]) % mod;
}
if(sum % 2 || !dp[sum / 2] || !ok) cout << 0;
else{
vector<int> valid(sum + 1);
for(int i = a[1] % 2; i <= sum; i += 2) valid[i] = true;
for(int i = 1; i <= n; i++){
vector<int> ndp = dp;
for(int j = a[i]; j <= sum; j++) ndp[j] = (ndp[j] - ndp[j - a[i]] + mod) % mod;
for(int j = a[1] % 2; j <= sum; j += 2) valid[j] &= (ndp[(sum - a[i] + j) / 2] > 0);
}
cout << accumulate(valid.begin(), valid.end(), 0ll) << "\n";
for(int i = 0; i <= sum; i++) if(valid[i]) cout << i << " ";
}
}
