#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int mod = 1e9 + 7;
int mul(int a, int b) { return (a * 1LL * b) % mod; }
int add(int a, int b) { return (a + b) % mod; }
int sub(int a, int b) { return (a - b + mod) % mod; }
const int N = 501;
int st[N * N]; // number of subsets that sum up to a certain value
int freq[N * N];
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<int> a(n);
for (int& u : a) cin >> u;
int sum = 0;
for (int& u : a) sum += u;
if (sum % 2 != 0) return cout << "0\n", 0;
auto add_contribution = [&](int x) {
for (int j = sum - x; j >= 0; --j) st[j + x] = add(st[j + x], st[j]);
};
auto remove_contribution = [&](int x) {
for (int j = 0; j <= sum - x; j++) st[j + x] = sub(st[j + x], st[j]);
};
st[0] = 1;
for (int i = 0; i < n; i++) {
add_contribution(a[i]);
}
if (st[sum / 2] == 0) return cout << "0\n", 0;
for (int i = 0; i < n; i++) {
remove_contribution(a[i]);
int S = 0;
for (int j = 0; j < n; j++) if (j != i) S += a[j];
freq[S] += 1;
for (int j = 1; j <= S - j && j < S; j++) if (st[j]) {
assert(st[S - j]);
freq[S - 2 * j] += 1;
}
add_contribution(a[i]);
}
int count_ans = 0;
for (int j = 0; j <= sum; j++) count_ans += (freq[j] == n);
cout << count_ans << "\n";
for (int j = 0; j <= sum; j++) if (freq[j] == n)
cout << j << " ";
cout << "\n";
}
