#include <bits/stdc++.h>
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define int long long
#define ff first
#define ss second
#define pb push_back
#define y1 zildjian
#define left radio
#define right head
using namespace std;
const int N = 501;
const int INF = 1e18;
const int mod = 1e9+7;
const int mod1 = 998244353;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
int n;
int a[N];
map<pair<int,int>,bool> m;
void solve(){
cin>>n;
int sum = 0;
for(int i = 1;i<=n;i++){
cin>>a[i];
sum+=a[i];
}
if(sum%2){
cout<<0;
return;
}
int dp[sum+1];
memset(dp,0,sizeof(dp));
for(int i = 2;i<=n;i++){
if(a[i]%2 != a[i-1]%2){
cout<<'0';
return;
}
}
dp[0] = 1;
for(int i = 1;i<=n;i++){
for(int w = sum;w>=a[i];w--){
dp[w] += dp[w-a[i]];
}
}
if(!dp[sum/2]){
cout<<0<<'\n';
return;
}
for(int i = 1;i<=n;i++){
vector<int> buf;
for(int w = 0;w<=sum;w++){
buf.pb(dp[w]);
}
for(int w = 0;w+a[i]<=sum;w++){
if(dp[w] && dp[w+a[i]]){
dp[w+a[i]] -= dp[w];
}
}
for(int w = 0;w<=sum;w++){
if(dp[w]) m[{w,i}] = 1;
dp[w] = buf[w];
}
}
int x = 1;
if(a[1]%2 == 0) x++;
vector<int> ans;
for(;x<=sum;x+=2){
bool ok = 1;
// cout<<x<<'\n';
for(int i = 1;i<=n;i++){
// w = (sum-a[i]+x)/2
// w-x = (sum-a[i]+x)/2-x;
if((sum-a[i]+x)%2 || !m[{(sum-a[i]+x)/2-x,i}]){
ok = 0;
break;
}
}
if(ok){
ans.pb(x);
}
}
// cout<<'\n';
cout<<ans.size()<<'\n';
for(auto x:ans) cout<<x<<' ';
cout<<'\n';
}
signed main(){
// freopen("bootfall.in","r",stdin);
// freopen("bootfall.out","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(nullptr);
// cout.tie(nullptr);
int t = 1;
// cin>>t;
for(int i = 1;i<=t;i++){
// cout<<"Case "<<i<<": ";
solve();
}
}
