// I ♡ 鞠婧祎
// #pragma GCC optimize("Ofast")
// #pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
#define freopen(name) if(fopen(name".INP","r")) {freopen (name".INP","r",stdin); freopen (name".OUT","w",stdout);}
using namespace std;
using ll = long long;
void justDoIt();
int main() {
// freopen("");
ios_base::sync_with_stdio(false);
cin.tie(0);
justDoIt();
return 0;
}
const int N = 505;
int a[N];
int dp[N * N], f[N * N];
bool used[N];
const int mod = 1e9 + 7;
int sum = 0;
void add(int x) {
for (int j = sum; j >= 0; j--) {
dp[j + x] += dp[j];
if (dp[j + x] >= mod) {dp[j + x] -= mod;}
}
sum += x;
}
void del(int x) {
sum -= x;
for (int j = 0; j <= sum; j++) {
dp[j + x] += (mod - dp[j]);
if (dp[j + x] >= mod) {dp[j + x] -= mod;}
}
}
void test() {
int n;
cin >> n;
bool odd = 0, even = 0;
int s = 0;
for (int i = 1; i <= n; i++) {
cin >> a[i];
s += a[i];
if (a[i] & 1) {odd = 1;}
else {even = 1;}
}
if (odd && even) {cout << 0; return;}
dp[0] = 1;
for (int i = 1; i <= n; i++) {
add(a[i]);
}
for (int i = 1; i <= n; i++) {
if (used[a[i]]) {continue;}
used[a[i]] = 1;
del(a[i]);
for (int j = 1; j <= s; j++) {
int cur = s - a[i] + j;
if (cur & 1 || !dp[cur / 2]) {
f[j] = 1;
}
}
add(a[i]);
}
vector<int> v;
for (int i = 1; i <= s; i++) {
if (!f[i]) {
v.push_back(i);
}
}
cout << v.size() << '\n';
for (auto it : v) {
cout << it << ' ';
}
}
void justDoIt() {
int t = 1;
// cin >> t;
for (int tests = 1; tests <= t; tests++) {
test();
}
}
