#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double cur = rngesus(0, MASK(60) - 1);
cur /= MASK(60) - 1;
return l + cur * (r - l);
}
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 T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
const ll MOD = 1000000007LL * 1000000009;
int main(void){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
clock_t start = clock();
int n; cin >> n;
vector<int> a(n);
for(int i= 0; i<n; ++i) cin >> a[i];
int s = 0;
for(int i: a) s += i;
vector<ll> dp(s + 1);
dp[0] = 1;
for(int i: a){
for(int j = s; j >= i; --j){
dp[j] += dp[j - i];
if (dp[j] >= MOD) dp[j] -= MOD;
}
}
if (s % 2 || dp[s / 2] == 0){
cout << 0 << "\n";
return 0;
}
vector<int> valid;
for(int i = 1; i<=s; ++i) valid.push_back(i);
for(int i: a){
for(int j = i; j <= s; ++j){
dp[j] -= dp[j - i];
if (dp[j] < 0) dp[j] += MOD;
}
int _s = s - i;
vector<int> tmp; tmp.reserve(valid.size());
for(int j: valid){
int l = (_s - j), r = (_s + j);
if (l >= 0 && l % 2 == 0 && dp[l / 2]){
tmp.push_back(j);
}
else if (r <= s * 2 && r % 2 == 0 && dp[r / 2]){
tmp.push_back(j);
}
}
valid = tmp;
for(int j = s; j >= i; --j){
dp[j] += dp[j - i];
if (dp[j] >= MOD) dp[j] -= MOD;
}
}
cout << valid.size() << "\n";
printArr(valid);
cerr << "Time elapsed: " << clock() - start << " ms\n";
return 0;
}
