#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ff(i,a,b) for(int i=a;i<=b;i++)
#define fb(i,b,a) for(int i=b;i>=a;i--)
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<int,int> pii;
const int maxn = 505;
const int inf = 1e9 + 5;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k) print the k-th smallest number in os(0-based)
int n;
int niz[maxn];
const int N = 500 * 500;
int dp[maxn * maxn];
int pomdp[maxn * maxn];
int cnt[maxn * maxn];
int main()
{
ios::sync_with_stdio(false);
cout.tie(nullptr);
cin.tie(nullptr);
cin >> n;
ff(i,1,n)cin >> niz[i];
dp[0] = 1;
ff(i,1,n){
fb(j,N,1){
if(j >= niz[i])dp[j] += dp[j - niz[i]];
}
}
int zbir = 0;
ff(i,1,n)zbir += niz[i];
if(zbir % 2 == 1 || dp[zbir / 2] == 0)return cout << 0, 0;
ff(i,1,n){
int x = niz[i];
ff(j,0,N)pomdp[j] = dp[j];
ff(j,1,N){
if(j >= x){
pomdp[j] -= pomdp[j - x];
}
}
int sum = zbir - x;
set<int> s;
ff(j,1,N){
if((sum + j) % 2 == 0 && pomdp[(sum + j) / 2] >= 1)s.insert(j);
}
for(auto c : s)cnt[c] += 1;
}
vector<int> vec;
ff(j,1,N){
if(cnt[j] == n)vec.pb(j);
}
cout << sz(vec) << endl;
sort(all(vec));
for(auto c : vec)cout << c << " ";
cout << endl;
return 0;
}
/**
4
200 200 200 200
6
3 5 7 11 9 13
4
1 3 1 5
3
2 2 2
// probati bojenje sahovski ili slicno
**/
