#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define mod 1000000007
#define sp << " " <<
#define endl << '\n'
vector<long long int> lst;
vector<long long int> sumplane;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
long long int N, sumall = 0;
cin >> N;
lst.resize(N);
sumplane.resize(500 * N);
for (int i = 0; i < N; i++){
cin >> lst[i];
sumall += lst[i];
}
sumplane[0] = 1;
for (int o = 0; o < N; o++){
for (int i = N * 500 - lst[o]; i >= 0; i--){
if (sumplane[i]){
sumplane[i + lst[o]] += sumplane[i];
}
}
}
if (sumall % 2 || sumplane[sumall / 2] == 0){
cout << 0;
return 0;
}
set<long long int> ret, newret;
vector<long long int> check(N * 500);
for (int o = 0; o < N; o++){
fill(all(check), 0);
for (int i = 500 * N - 1; i >= (sumall + lst[o] + 1) / 2; i--){
if (check[i] == sumplane[i]){
check[i] = 0;
continue;
}
check[i - lst[o]] += sumplane[i] - check[i];
check[i] = 1;
}
for (int i = (sumall + lst[o] + 1) / 2; i < N * 500; i++){
if (o){
if (check[i]){
if (ret.find(2 * i - sumall - lst[o]) != ret.end())
newret.insert(2 * i - sumall - lst[o]);
}
}else{
if (check[i]){
newret.insert(2 * i - sumall - lst[0]);
}
}
}
ret.swap(newret);
newret.clear();
}
cout << ret.size() endl;
for (auto k : ret)
cout << k sp "";
}
