#include<bits/stdc++.h>
using namespace std;
const int maxN = 500 + 3;
const int bsSize = maxN * maxN + 10;
int n;
int a[maxN];
int cnt[maxN];
bitset<bsSize> dp[2][maxN], pre;
int main() {
//cin >> n;
n = 500;
int sum = 0;
int gc = 0;
for (int i = 1; i<=n; i++) {
//cin >> a[i];
a[i] = min(2 * i - 1, 499);
gc = __gcd(a[i], gc);
}
for (int i = 1; i<=n; i++) {
a[i]/=gc;
if ((a[i] & 1) == 0) {
printf("0\n");
return 0;
}
cnt[a[i]]++;
sum+=a[i];
}
if (sum & 1) {
printf("0\n");
return 0;
}
for (int i = 1; i <= 501; i++) {
dp[0][i].set(0);
}
int par = 0;
for (int i = 1; i < 500; i+=2) {
bool updated = false;
par^=1;
for (int j = 1; j <= 501; j+=2) {
if (j < 501 && !cnt[j]) continue;
if (i == j) {
dp[par][j] = dp[par ^ 1][j] | (dp[par ^ 1][j] << (j * (cnt[j]-1)));
} else {
if (updated) {
dp[par][j] = pre;
} else {
dp[par][j] = dp[par ^ 1][j] | (dp[par ^ 1][j] << (j * cnt[j]));
if (i < j && !updated) {
pre = dp[par][j];
updated = true;
}
}
}
}
}
if (dp[par][501][sum/2] == 0) {
printf("0\n");
return 0;
}
vector<int> ans;
for (int i = 1; i <= sum; i+=2) {
bool ok = true;
for (int j = 1; j < 500; j+=2) {
if (!cnt[j]) continue;
int totSum = sum - j + i;
if (totSum % 2 == 1) ok = false;
if (dp[par][j][totSum/2] == 0) ok = false;
}
if (ok) ans.push_back(i);
}
cout << ans.size() << endl;
for (int i:ans) {
printf("%d ", i * gc);
}
cout << endl;
}
