#include "bits/stdc++.h"
using namespace std;
int32_t main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
int n;
cin >> n;
vector <int> a(n + 1, 0);
int sm = 0;
for (int i = 1; i <= n; i++) {
cin >> a[i];
sm += a[i];
}
if (sm % 2) return cout << 0, 0;
int m = (sm + 3000)>>1;
vector <int> dp(m + 1, 0);
dp[0] = 1;
for (int i = 1; i <= n; i++) {
for (int j = m - a[i]; j >= 0; j--) dp[j + a[i]] += dp[j];
}
if (!dp[sm>>1]) return cout << 0, 0;
vector <int> ans;
int x = 0;
while (++x <= 3000) {
int smv = sm + x;
int mv = smv>>1;
vector <int> v = a; v.push_back(x);
vector <int> can = dp;
for (int i = mv; i >= x; i--) can[i] += can[i - x];
bool tr = true;
for (int i = 1; i <= n + 1; i++) {
if ((smv - v[i]) % 2) {
tr = false;
break;
}
for (int j = v[i]; j <= mv; j++) can[j] -= can[j - v[i]];
if (!can[(smv - v[i])>>1]) {
tr = false;
break;
}
for (int j = mv; j >= v[i]; j--) can[j] += can[j - v[i]];
}
if (tr) ans.push_back(x);
}
cout << (int)ans.size() << '\n';
for (auto i : ans) cout << i << ' ';
}
