# include <stdio.h>
# include <bits/stdc++.h>
#define _USE_MATH_DEFINES_
#define ll long long
#define ld long double
#define Accepted 0
#define pb push_back
#define mp make_pair
#define sz(x) (int)(x.size())
#define every(x) x.begin(),x.end()
#define F first
#define S second
#define For(i,x,y) for (int i = x; i <= y; i ++)
#define FOr(i,x,y) for (int i = x; i >= y; i --)
#define SpeedForce ios_base::sync_with_stdio(0), cin.tie(0)
// ROAD to... Red
using namespace std;
inline bool isvowel (char c) {
c = tolower(c);
if (c == 'a' || c == 'e' || c == 'i' || c == 'y' || c == 'o' || c == 'u') return 1;
return 0;
}
const double eps = 0.000001;
const ld pi = acos(-1);
const int maxn = 1e7 + 9;
const int mod = 1e9 + 7;
const ll MOD = 1e18 + 9;
const ll INF = 1e18 + 123;
const int inf = 2e9 + 11;
const int mxn = 1e6 + 9;
const int N = 6e5 + 123;
const int M = 22;
const int pri = 997;
const int Magic = 2101;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};
int n, m, k;
int a[N], sum;
ll dp[N];
int can[N];
void add (int x) {
sum += x;
for (int i = sum; i >= x; i --)
dp[i] += dp[i - x];
}
void del (int x) {
for (int i = x; i <= sum; i ++)
dp[i] -= dp[i - x];
sum -= x;
}
int main () {
SpeedForce;
cin >> n;
dp[0] = 1;
For (i, 1, n ) {
cin >> a[i];
add (a[i]);
}
if (sum & 1 || !dp[sum / 2]) {
cout << 0 << '\n';
exit(0);
}
For (i, 1, sum) can[i] = 1;
For (i, 1, n) {
del(a[i]);
For (j, 1, sum + a[i]) {
if ((sum + j) % 2 != 0 || !dp[(sum + j) / 2]) {
can[j] = 0;
}
}
add(a[i]);
}
vector < int > ans;
For (i, 1, sum) if (can[i]) ans.pb(i);
cout << sz(ans) << '\n';
for (auto it : ans) cout << it << ' ';
return Accepted;
}
// Coded By OB
