#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int N;
cin >> N;
vector<int> A(N);
for (int i = 0; i < N; i++) {
cin >> A[i];
}
const int MAX = accumulate(begin(A), end(A), 0) + 5;
const int MOD = 1e9 + 7;
const auto Add = [&](int &a, int b) {
a += b;
if (a >= MOD) a -= MOD;
};
int sum = 0;
vector<int> dp(MAX);
dp[0] = 1;
const auto Insert = [&](int a) {
sum += a;
for (int i = MAX - 1; i >= 0; i--) {
if (i + a < MAX) {
Add(dp[i + a], dp[i]);
}
}
};
const auto Delete = [&](int a) {
sum -= a;
for (int i = 0; i < MAX; i++) {
if (i + a < MAX) {
Add(dp[i + a], MOD - dp[i]);
}
}
};
for (int i = 0; i < N; i++) {
Insert(A[i]);
}
if (sum % 2 != 0 || dp[sum / 2] == 0) {
cout << 0 << '\n';
return 0;
}
vector<int> ans(MAX);
for (int i = 0; i < N; i++) {
Delete(A[i]);
for (int j = 1; j < MAX; j++) {
int nsum = sum + j;
if (nsum % 2 != 0) continue;
int need = nsum / 2;
if ((0 <= need - 0 && need - 0 < MAX && dp[need - 0] != 0) ||
(0 <= need - j && need - j < MAX && dp[need - j] != 0)) {
ans[j]++;
}
}
Insert(A[i]);
}
vector<int> answer;
for (int i = 1; i < MAX; i++) {
if (ans[i] == N) {
answer.emplace_back(i);
}
}
cout << answer.size() << '\n';
for (auto a : answer) {
cout << a << ' ';
}
cout << '\n';
return 0;
}
