#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 505;
const int MX = 500 * 500 + 5;
const int mod = 1e9 + 7;
int a[N], d[MX], cnt[MX], Sum;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int n;
cin >> n;
d[0] = 1;
for (int i = 1 ; i <= n ; ++ i) {
cin >> a[i];
Sum += a[i];
for (int j = MX - 1 ; j >= a[i] ; -- j) {
d[j] += d[j - a[i]];
d[j] -= d[j] >= mod ? mod : 0;
}
}
if (Sum & 1 || !d[Sum / 2]) return cout << "0", 0;
for (int i = 1 ; i <= n ; ++ i) {
int Now = Sum - a[i];
//cout << i << " " << Now << endl;
for (int j = a[i] ; j < MX ; ++ j) {
d[j] -= d[j - a[i]];
d[j] += d[j] < 0 ? mod : 0;
}
for (int j = Now & 1 ; j < MX ; j += 2) {
int Cur = Now + j;
cnt[j] += j <= (Cur >> 1) && !!d[(Cur >> 1) - j];
}
for (int j = MX - 1 ; j >= a[i] ; -- j) {
d[j] += d[j - a[i]];
d[j] -= d[j] >= mod ? mod : 0;
}
}
int Cnt = 0;
for (int i = 0 ; i < MX ; ++ i) Cnt += cnt[i] == n;
cout << Cnt << "\n";
for (int i = 0 ; i < MX ; ++ i) if (cnt[i] == n) cout << i << " ";
}
