#include<bits/stdc++.h>
using namespace std;
#ifndef BADGNU
#pragma GCC target("sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#endif
#pragma GCC optimize("Ofast,unroll-loops,fast-math,O3")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ll long long
#define int ll
#define ld long double
#define y1 cheza
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class T> using ordered_set = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
template<class T> using ordered_multiset = tree<T,null_type,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;
const int N=510;
const int M=500*500+10;
const int B=447;
const int mod=998244353;
const ll INF=1e18;
const int dx[]={1,-1,0,0};
const int dy[]={0,0,1,-1};
const double eps=1e-6;
int n;
int a[N];
bitset<M>dp;
bitset<M>f[N];
void test(){
cin>>n;
int sum=0;
for(int i=1;i<=n;i++){
cin>>a[i];
sum+=a[i];
}
sort(a+1,a+n+1);
dp[0]=1;
for(int i=1;i<=n;i++){
f[i]=dp;
for(int j=i+1;j<=n;j++){
f[i]|=(f[i]<<a[j]);
}
dp|=(dp<<a[i]);
}
int mask=0;
for(int i=1;i<=n;i++){
if(a[i]%2){
mask|=1;
}
else{
mask|=2;
}
}
if(sum%2||dp[sum/2]==0||mask==3){
cout<<0<<'\n'<<'\n';
return;
}
vector<int>v;
for(int j=mask;j<=250000;j+=2){
v.push_back(j);
for(int i=1;i<=n;i++){
int cur=(sum-a[i]+j);
if(cur%2){
v.pop_back();
break;
}
cur/=2;
if(f[i][cur]){
continue;
}
if(cur>=j&&f[i][cur-j]){
continue;
}
v.pop_back();
break;
}
}
cout<<v.size()<<'\n';
for(auto i:v){
cout<<i<<' ';
}
cout<<'\n';
}
/*
*/
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// cout.tie(nullptr);
int t2=1;
// cin>>t2;
for(int i=1;i<=t2;i++){
test();
}
}
