//stupid solution 1
#include <bits/stdc++.h>
#pragma GCC optimize("-Ofast")
//#pragma GCC optimize("trapv")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-funroll-loops")
#define vi vector<int>
#define vii vector<pair<int, int>>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define loop(_) for (int __ = 0; __ < (_); ++__)
#define forn(i, n) for (int i = 0; i < n; ++i)
using namespace std;
using ll = long long;
using ld = long double;
const int N = 500 + 7;
const int NN = N * N;
const ll mod = 1e9 + 7;
const ll inf = 2e18;
auto ra = [] {char *p = new char ; delete p ; return ll(p) ; };
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count() * (ra() | 1));
int n;
int ret[NN];
vi a;
bitset<NN> pref[N], suff[N];
void eval(bitset<NN> &ret, int l, int r, int d)
{
if (d == 1)
for (int i = l; i <= r; ++i)
ret |= (ret << a[i]);
else
for (int i = r; i >= l; --i)
ret |= (ret << a[i]);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("in.in", "r", stdin);
cin >> n;
vi ans;
a.resize(n);
int sum = 0;
for (auto &u : a)
cin >> u;
sum = accumulate(a.begin(), a.end(), 0);
bitset<NN> ini, ini2;
ini[0] = ini2[0] = 1;
for (int i = 0; i < n; ++i)
{
ini |= (ini << a[i]);
ini2 |= (ini2 << a[n - 1 - i]);
suff[n - 1 - i] = ini2;
pref[i] = ini;
}
if (sum & 1 || !pref[n - 1][sum / 2])
return cout << 0, 0;
for (int i = 0; i < n; ++i)
{
int sm = sum - a[i];
int lhs = i, rhs = n - 1 - i;
bitset<NN> bts;
if (lhs > rhs)
{
if (i)
bts = pref[i - 1];
eval(bts, i + 1, n - 1, 1);
}
else
{
if (i + 1 < n)
bts = suff[i + 1];
eval(bts, 0, i - 1, -1);
}
for (int j = 0; j <= sm; ++j)
{
if (bts[j])
{
if (2 * j != sm)
ret[abs(j - (sm - j))]++;
}
}
}
int sz = 0;
for (int u = 1; u < NN; ++u)
{
if (ret[u] == 2 * n)
ans.push_back(u);
}
cout << (int)ans.size() << "\n";
for (auto u : ans)
cout << u << " ";
return 0;
}
