#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18
#define INF (ll)1e9
#define MOD (ll)(1e9 + 7)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
const int MAX = 503;
int N;
int a[MAX], f[MAX * MAX];
void solve(){
cin >> N;
int S = 0;
for(int i = 1; i <= N; i++){
cin >> a[i];
S += a[i];
}
f[0] = 1;
for(int i = 1; i <= N; i++){
for(int j = S; j >= a[i]; j--){
f[j] += f[j - a[i]];
}
}
if(S % 2 || !f[S / 2]){
cout << 0 << '\n';
return;
}
vector<int> ans;
for(int i = 1; i <= S; i++) ans.push_back(i);
for(int i = 1; i <= N; i++){
for(int j = a[i]; j <= S; j++) f[j] -= f[j - a[i]];
vector<int> tmp;
tmp.reserve(sz(ans));
for(int x: ans){
int tS = S - a[i] + x;
if(tS % 2 == 0 && f[tS / 2]){
tmp.push_back(x);
}
}
ans = tmp;
for(int j = S; j >= a[i]; j--) f[j] += f[j - a[i]];
}
cout << sz(ans) << '\n';
for(int x: ans) cout << x << ' ';
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("order.inp","r",stdin);
// freopen("order.out","w",stdout);
solve();
return 0;
}
