#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 500*500;
typedef bitset<2*MX+1> B;
int N, a[500];
B all;
bitset<500> al;
B gen(bitset<500> tmp) {
B b; b[MX] = 1;
F0R(i,N) if (tmp[i]) b = (b<<a[i])|(b>>a[i]);
return b;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
all.flip(); al.flip();
cin >> N;
F0R(i,N) cin >> a[i];
if (gen(al)[MX] == 0) {
cout << 0;
exit(0);
}
F0R(i,N) {
al[i] = 0;
all &= gen(al);
al[i] = 1;
}
vi v;
FOR(i,1,MX+1) if (all[MX+i]) v.pb(i);
cout << sz(v) << "\n";
for (int i: v) cout << i << " ";
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
