#include <bits/stdc++.h>
using namespace std;
const int N = 5e2 + 5;
const int S = N * N;
int cur [S];
int nxt [S];
int without [S];
bitset<S> ans;
bitset<S> Get;
int main () {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<int> a (n);
for (int i = 0; i < n; i++) cin >> a[i];
int whole_sum = accumulate (a.begin(), a.end(), 0);
cur[0] = nxt[0] = 1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < S; j++) {
nxt[j] = cur[j];
if (j - a[i] >= 0) nxt[j] += cur[j - a[i]];
}
for (int j = 0; j < S; j++) {
cur[j] = nxt[j];
nxt[j] = 0;
}
nxt[0] = 1;
}
if ((whole_sum & 1) || (cur[whole_sum / 2] == 0) ) {
cout << 0 << '\n';
return 0;
}
/*
for (int i = 0; i <= 10; i++) {
cout << i << ' ' << cur[i] << '\n';
}
cout << '\n';
*/
ans.set();
for (int i = 0; i < n; i++) {
whole_sum -= a[i];
for (int j = 0; j < S; j++) {
without[j] = cur[j];
}
// Remover o efeito da moeda i
for (int j = a[i]; j < S; j++) {
if (without[j]) without[j] -= without[j - a[i]];
}
Get.reset();
for (int j = 0; j <= whole_sum; j++) {
if (without[j]) {
int left = j;
int right = whole_sum - j;
Get[abs(left - right)] = 1;
}
}
ans &= Get;
whole_sum += a[i];
}
cout << ans.count() << '\n';
for (int i = 0; i < S; i++) if (ans[i]) cout << i << ' ';
return 0;
}
