#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pr;
#define fr first
#define sc second
#define FOR(i, a) for (int i = 0; i < (a); i++)
#define F0R(i, a, b) for (int i = (a); i <= (b); i++)
#define FORd(i,a) for (int i = (a)-1; i >= 0; i--)
#define F0Rd(i,a,b) for (int i = (b); i >= (a); i--)
#define trav(a, x) for (auto& a : x)
const int N=5000006;
int sum;
int a[N];
ll dp[N];
bool cant[N];
void add(ll k){
sum+=k;
for (int i=sum;i>=k;i--){
dp[i]+=dp[i-k];
}
}
void rem(ll k){
for (int i=k;i<=sum;i++){
dp[i]-=dp[i-k];
}
sum-=k;
}
int main(){
ios_base::sync_with_stdio(false);
#ifndef EVAL
freopen("input.txt","r",stdin);
#endif
int n;
cin>>n;
dp[0]=1;
FOR(i,n){
cin>>a[i];
add(a[i]);
}
if (sum%2==1 || dp[sum/2]==0){
//cout<<dp[sum/2]<<endl;
cout<<0<<endl;
return 0;
}
int hn=sum;
FOR(i,n){
rem(a[i]);
FOR(j,hn+1){
//cout<<a[i]<<" "<<j<<" "<<dp[j]<<endl;
if ((sum+j)%2==1 || dp[(sum+j)/2]==0){
cant[j]=true;
}
}
add(a[i]);
}
int ans=0;
FOR(j,hn+1)
if (!cant[j])
ans++;
cout<<ans<<endl;
FOR(j,hn+1)
if (!cant[j])
cout<<j<<" ";
return 0;
}
