// アイスクリーム
#include <bits/stdc++.h>
#ifndef alks
#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
#endif
#pragma GCC optimize("O3,unroll-loops")
#define ll long long
#define int ll
#define Yes cout<<"YES\n"; return;
#define No cout<<"NO\n"; return;
#define yes cout<<"Yes\n"; return;
#define no cout<<"No\n"; return;
#define wrans cout<<"-1\n"; return;
using namespace std;
const int N=2e6;
const int M=1e6+100;
const int mod1=998244353;
const int mod=1e9+7;
const int INF=1e18;
const long double eps=1e-12;
const string ab="abcdefghijklmnopqrstuvwxyz";
const string AB="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
int n;
int a[(int)555];
int dp[N];
int dp1[N];
map <pair<int,int>, int> m;
void alikosh(){
cin>>n;
int sum=0;
for(int i=1;i<=n;i++){
cin>>a[i];
sum+=a[i];
}
dp[0]=dp1[0]=1;
for(int i=1;i<=n;i++){
for(int s=sum;s>=a[i];s--){
dp[s]+=dp[s-a[i]];
dp1[s]=dp[s];
dp[s]%=mod;
dp1[s]%=mod;
}
}
vector <int> ans;
for(int i=1;i<=n;i++){
for(int s=0;s<=sum-a[i];s++){
if(dp1[s] && dp1[s+a[i]]){
dp1[s+a[i]]-=dp1[s];
dp1[s+a[i]]=(dp1[s+a[i]]%mod+mod)%mod;
}
}
for(int s=0;s<=sum;s++){
if(dp1[s]){
m[{s,i}]++;
}
dp1[s]=dp[s];
}
}
for(int x=1+1-(a[1] & 1);x<=sum;x+=2){
bool ok=0;
for(int i=1;i<=n;i++){
int y=sum+x-a[i];
if(y & 1){
ok=1;
break;
}
if(m[{y/2-x,i}]==0){
ok=1;
break;
}
}
if(!ok){
ans.push_back(x);
}
}
if(dp[sum/2]==0 || sum%2 || n%2){
cout<<"0\n";
return;
}
cout<<ans.size()<<"\n";
for(int i:ans){
cout<<i<<' ';
}
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int alikosh1=1;
// cin>>alikosh1;
for(int i=1;i<=alikosh1;i++){
// cout<<"Case "<<i<<": ";
alikosh();
}
}
//, Ice \ \
