#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;
const int C = mxn*(mxn-1)/2;
int mod = 998244353;
int arr[mxn];
int dp[C];
int del[mxn][C];
int n;
int sum = 0;
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){
if(sum&1)return false;
if(!dp[sum>>1])return false;
int tsum = sum+now;
for(int i = 1;i<=n;i++){
tsum -= arr[i];
if(tsum&1)return false;
if(tsum/2<now)return false;
if(!del[i][tsum>>1])return false;
tsum += arr[i];
}
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]]);
}
for(int i = 1;i<=n;i++){
for(int j = 0;j<C;j++)del[i][j] = dp[j];
for(int j = arr[i];j<C;j++)del[i][j] = mub(del[i][j],del[i][j-arr[i]]);
}
vector<int> ans;
for(int i = 1;i<C;i++){
if(check(i))ans.push_back(i);
}
vector<int> ans2;
mod = 1e9+7;
memset(dp,0,sizeof(dp));
dp[0] = 1;
for(int i = 1;i<=n;i++){
for(int j = C-1;j>=arr[i];j--)dp[j] =mad(dp[j],dp[j-arr[i]]);
}
for(int i = 1;i<=n;i++){
for(int j = 0;j<C;j++)del[i][j] = dp[j];
for(int j = arr[i];j<C;j++)del[i][j] = mub(del[i][j],del[i][j-arr[i]]);
}
for(auto &i:ans){
if(check(i))ans2.push_back(i);
}
swap(ans,ans2);
ans2.clear();
/*
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;
}
