#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<double> vd;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<pi> vp;
typedef vector<pl> vpl;
void no(){
cout << "0\n";
exit(0);
}
const int M = 500*500;
int d[M+505], dp[M+505], a[M+505], cnt[M+505], vis[M+505];
vi sol;
int main()
{
int n;
cin >> n;
int suma = 0;
for (int i = 0; i < n; ++i){
cin >> a[i];
suma += a[i];
}
if (suma%2) no();
dp[0]=1;
for (int i = 0; i < n; ++i){
for (int j = M; j > -1; --j){
dp[a[i]+j] += dp[j];
}
}
if (!dp[suma/2]) no();
int b = 0;
for (int i = 0; i < n; ++i){
if (vis[a[i]]){
++b;
continue;
}
memset(d, 0, sizeof(d));
for (int j = 0; j <= M; ++j){
d[j] += dp[j];
d[j+a[i]] -= d[j];
}
for (int j = 0; j <= M; ++j){
if ((suma-a[i]+j)%2 == 0 && suma-a[i]-j>=0 && d[(suma-a[i]-j)/2]){
++cnt[j];
}
}
}
for (int i = 1; i <= M; ++i)
if (cnt[i] == n-b)
sol.push_back(i);
cout << (int)sol.size() << '\n';
for (auto& i : sol)
cout << i << ' ';
}
