///////////////////////////
// INFO //
// //
// Handle -> Scayre //
// //
// Template vers. 1.1 //
// //
// It'll be accepted //
// //
///////////////////////////
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#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <complex>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <cassert>
#include <iomanip>
#include <iostream>
#include <algorithm>
#define ll long long
#define ld long double
#define ull unsigned ll
#define ioi exit(0);
#define f first
#define s second
#define inf (int)1e9 + 7
#define NFS ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0);
#define mp(x,y) make_pair(x,y)
#define lb(x) lower_bound(x)
#define ub(x) upper_bound(x)
#define pb push_back
#define ppb pop_back
#define bitcoin __builtin_popcount
#define endl "\n"
#define in(x) insert(x)
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define pw2(x) (1<<x) //2^x
#define forit(it,v) for (typeof(v.begin()) it = v.begin(); it != v.end(); ++it)
#define sqr(x) ((x) * 1ll * (x))
#define UpdateRandom srand (time(NULL));
using namespace std;
const int N = (int)5e5 + 7, MOD = (int)1e9 + 7;
int n;
int a[N];
ll sum;
ll dp[N];
int u[N];
vector<int> v;
void add(int x){
sum+=x;
for(int i=sum;i>=x;i--){
dp[i]+=dp[i-x];
}
}
void del(int x){
for(int i=x;i<=sum;i++){
dp[i]-=dp[i-x];
}
sum-=x;
}
int main(){
#ifdef IOI2019
freopen ("in.txt", "r", stdin);
#endif
NFS
cin >> n;
dp[0]=1;
for(int i=1;i<=n;i++){
cin >> a[i];
add(a[i]);
}
if(sum%2!=0 || dp[sum/2]==0){
cout << 0 << endl;
ioi
}
for(int i=1;i<=n;i++){
del(a[i]);
for(int j=1;j<=sum+a[i];j++){
if(dp[(sum+j)/2]==0 || (sum+j)%2!=0){
u[j]=1;
}
}
add(a[i]);
}
for(int i=1;i<=sum;i++){
if(!u[i]){
v.pb(i);
}
}
cout << sz(v) << endl;
for(int i=0;i<sz(v);i++){
cout << v[i] << ' ';
}
#ifdef IOI2019
cout << "\nTime Elapsed : " << clock () * 1.0 / CLOCKS_PER_SEC << endl;
#endif
ioi
}
