#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll,ll>
#define pii pair<int,int>
#define fs first
#define sc second
#define tlll tuple<ll,ll,ll>
const int mxn = 510*2;
const int C = mxn*mxn;
int mod = 998244353;
int arr[mxn];
int dp[C];
int del[C];
int n;
int sum = 0;
bitset<C> able;
inline ll mad(int a,int b){
a += b;
return a>=mod?a-mod:a;
}
inline ll mub(int a,int b){
return mad(a,mod-b);
}
inline bool check(int now,int tsum){
if(sum&1)return false;
if(!dp[sum>>1])return false;
if(tsum&1)return false;
if(tsum/2<now)return false;
if(!del[tsum>>1])return false;
return true;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>n;
dp[0] = 1;
for(int i = 1;i<=n;i++){
cin>>arr[i];
sum += arr[i];
for(int j = C-1;j>=arr[i];j--)dp[j] =mad(dp[j],dp[j-arr[i]]);
}
set<int> ans;
able.set();
for(int i = 1;i<=n;i++){
for(int j = 0;j<C;j++)del[j] = dp[j];
for(int j = arr[i];j<C;j++)del[j] = mub(del[j],del[j-arr[i]]);
for(int j = 1;j<=sum;j++){
if(!check(j,sum-arr[i]+j))able[j] = false;
}
}
for(int j = 1;j<=sum;j++)if(able[j])ans.insert(j);
memset(dp,0,sizeof(dp));
mod = 998244353;
dp[0] = 1;
able.set();
for(int i = 1;i<=n;i++){
for(int j = 0;j<C;j++)del[j] = dp[j];
for(int j = arr[i];j<C;j++)del[j] = mub(del[j],del[j-arr[i]]);
for(int j = 1;j<=sum;j++){
if(!check(j,sum-arr[i]+j))able[j] = false;
}
}
for(int j = 1;j<=sum;j++)if(able[j])ans.insert(j);
/*
for(int i = 0;i<=10;i++)cout<<dp[i]<<' ';cout<<endl;
cout<<sum<<endl;
cout<<endl;
for(int i = 1;i<=n;i++){
for(int j = 0;j<=10;j++)cout<<del[i][j]<<' ';cout<<endl;
}
*/
cout<<ans.size()<<'\n';
for(auto &i:ans)cout<<i<<' ';
return 0;
}
