#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MOD1 = (int)1e9 + 7;
const int MOD2 = 998244353;
const int MOD3 = (int)1e9 + 9;
int n;
int A[505];
int ways[505*505][3];
int cnt[505*500];
int32_t main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
vector<int> MODS={MOD1,MOD2,MOD3};
cin>>n;
int sum=0;
for(int i=1;i<=n;i++){
cin>>A[i];
sum+=A[i];
}
ways[0][0]=1;
ways[0][1]=1;
ways[0][2]=1;
for(int i=1;i<=n;i++){
for(int j=sum;j>=0;j--){
for(int k=0;k<=2;k++){
if(j-A[i]>=0)ways[j][k]=(ways[j][k]+ways[j-A[i]][k])%MODS[k];
}
}
}
unordered_set<int>os;
if(sum % 2 == 1){
return cout << 0,0;
}
if(ways[sum/2][0] == 0 && ways[sum/2][1] == 0 && ways[sum/2][2] == 0){
return cout << 0,0;
}
for(int i=1;i<=n;i++){ // remove this
unordered_set<int>os;
for(int j=0;j<=sum;j++){
for(int k=0;k<=2;k++){
if(j-A[i]>=0)ways[j][k]=(ways[j][k]-ways[j-A[i]][k]+MODS[k])%MODS[k];
}
if(ways[j][0] != 0 && ways[j][1] != 0 && ways[j][2] != 0){
int diff=abs(j-((sum-A[i])-j));
os.insert(diff);
}
}
for(auto x:os){
if(x>=0)cnt[x]++;
}
for(int j=sum;j>=0;j--){
for(int k=0;k<=2;k++){
if(j-A[i]>=0)ways[j][k]=(ways[j][k]+ways[j-A[i]][k])%MODS[k];
}
}
}
vector<int>out;
for(int j=1;j<=sum;j++){
if(cnt[j] == n){
out.push_back(j);
}
}
cout<<out.size()<<"\n";
for(auto x:out)cout<<x<<" ";
}
