#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2")
#define ll long long
#define int ll
#define ull unsigned ll
#define ld long double
#define rep(a) rep1(i,a)
#define rep1(i,a) rep2(i,0,a)
#define rep2(i,b,a) for(int i=(b); i<((int)(a)); i++)
#define rep3(i,b,a) for(int i=(b); i>=((int)(a)); i--)
#define chkmin(a,b) (a=min(a,b))
#define chkmax(a,b) (a=max(a,b))
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define pb push_back
//#define inf 1010000000
#define inf 4000000000000000000
#define eps 1e-9
#define sz(a) ((int)a.size())
#define pow2(x) (1ll<<(x))
#define ceiling(a,b) (((a)+(b)-1)/(b))
#define print0(a) cout << (a) << ' '
#define ykh mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#ifdef i_am_noob
#define bug(...) cerr << "#" << __LINE__ << ' ' << #__VA_ARGS__ << "- ", _do(__VA_ARGS__)
template<typename T> void _do(T && x) {cerr << x << endl;}
template<typename T, typename ...S> void _do(T && x, S&&...y) {cerr << x << ", "; _do(y...);}
#else
#define bug(...) 777771449
#endif
const int mod=1000000007;
const int maxn=505,maxm=18,maxk=7777714;
//i_am_noob
int n,a[maxn],sum;
bitset<maxn*maxn> bs[maxn];
bool vis[maxn];
void orzck(){
cin >> n;
rep(n) cin >> a[i];
sum=accumulate(a,a+n,0ll);
bitset<maxn*maxn> b;
b[0]=1;
rep(n) b|=b<<a[i];
if((sum&1)||!b[sum/2]){
cout << "0\n";
return;
}
rep(n) if((a[0]+a[i])&1){
cout << "0\n";
return;
}
b.set();
rep(n) if(!vis[a[i]]){
bs[i][0]=1;
rep1(j,n) if(i!=j) bs[i]|=bs[i]<<a[j];
bs[i]<<=a[i]/2;
vis[a[i]]=1;
b&=bs[i];
}
vector<int> res;
rep2(i,1,sum+1) if((i+a[0])%2==0){
if(b[(sum+i)/2]) res.pb(i);
}
cout << sz(res) << "\n";
for(auto i: res) cout << i << ' ';
cout << "\n";
}
signed main(){
ios_base::sync_with_stdio(0),cin.tie(0);
orzck();
return 0;
}
