#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 500 + 2;
const int mod = 1e9 + 7;
int a[N], cnt[N * N], dp92[N * N], dpc[N * N];
int Add(int a, int b) {
a += b;
while (a >= mod) a -= mod;
while (a < 0) a += mod;
return a;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
int sum = 0;
dp92[0] = 1;
for (int i = 1; i <= n; i++) {
cin >> a[i];
sum += a[i];
for (int j = sum; j >= a[i]; j--) {
dp92[j] = Add(dp92[j], dp92[j - a[i]]);
}
}
if (sum % 2 == 1 || dp92[sum / 2] == 0) {
cout << 0 << en;
return 0;
}
for (int i = 1; i <= n; i++) {
for (int j = 0; j < a[i]; j++) dpc[j] = dp92[j];
for (int j = a[i]; j <= sum; j++) dpc[j] = Add(dp92[j], -dpc[j - a[i]]);
for (int j = 0; j <= sum; j++) {
int x = 2 * j + a[i] - sum;
if (dpc[j] > 0 && x > 0) cnt[x] += 1;
}
}
vector<int> ans;
for (int i = 1; i <= sum; i++) if (cnt[i] == n) ans.push_back(i);
cout << ans.size() << en;
for (int i : ans) cout << i << sp;
cout << en;
return 0;
}
