#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ar array
#define fr first
#define sc second
#define vec vector
#define ret return
#define ins insert
#define mk make_pair
#define pb push_back
#define pf push_front
#define pob pop_back
#define pof pop_back
#define int long long
#define pii pair<int,int>
#define all(s) s.begin(), s.end()
#define allr(s) s.rbegin(), s.rend()
#define NeedForSpeed ios::sync_with_stdio(0),cin.tie(0);
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
const int N=1e6+12,INF=1e9,mod = 1e9+7;
bool iswowel(char n){ n = toupper(n); if(n == 'A' || n == 'O' || n == 'U' || n == 'E' || n == 'I') return true; else return false;}
int n,m,k,x,y,l,r,o,ans,res,ok,mx,mn = INF;
int a[N],b[N],dp[N],c;
set<int>s;
void add(int v){
for(int i=res; i>=0; i--)dp[i + v] += dp[i];
res += v;
}
void del(int v){
res -= v;
for(int i=0; i<=res; ++i)dp[i + v] -= dp[i];
}
main(){
NeedForSpeed
cin>>n;
dp[0] = 1;
for(int i=0; i<n; i++){
cin>>a[i];
add(a[i]);
ans += a[i];
}
if((ans) % 2 || !dp[(ans)/2]){
cout<<0<<endl;
ret 0;
}
for(int i=0; i<n; i++){
del(a[i]);
for(int j=1; j<=ans; j++){
if((res+j) % 2 || !dp[(res+j)/2])b[j] = 1;
}
add(a[i]);
}
for(int i=1; i<=ans; i++)if(!b[i])s.ins(i);
cout<<s.size()<<endl;
for(int i : s)cout<<i<<" ";
return 0;
}
