#include <bits/stdc++.h>
using namespace std ;
#define int int64_t //be careful about this
#define endl "\n"
#define f(i,a,b) for(int i=int(a);i<int(b);++i)
#define pr pair
#define ar array
#define fr first
#define sc second
#define vt vector
#define pb push_back
#define eb emplace_back
#define LB lower_bound
#define UB upper_bound
#define PQ priority_queue
#define sz(x) ((int)(x).size())
#define all(a) (a).begin(),(a).end()
#define allr(a) (a).rbegin(),(a).rend()
#define mem0(a) memset(a, 0, sizeof(a))
#define mem1(a) memset(a, -1, sizeof(a))
template<class A> void rd(vt<A>& v);
template<class T> void rd(T& x){ cin >> x; }
template<class H, class... T> void rd(H& h, T&... t) { rd(h) ; rd(t...) ;}
template<class A> void rd(vt<A>& x) { for(auto& a : x) rd(a) ;}
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
template<typename T>
void __p(T a) {
cout<<a;
}
template<typename T, typename F>
void __p(pair<T, F> a) {
cout<<"{";
__p(a.first);
cout<<",";
__p(a.second);
cout<<"}\n";
}
template<typename T>
void __p(std::vector<T> a) {
cout<<"{";
for(auto it=a.begin(); it<a.end(); it++)
__p(*it),cout<<",}\n"[it+1==a.end()];
}
template<typename T, typename ...Arg>
void __p(T a1, Arg ...a) {
__p(a1);
__p(a...);
}
template<typename Arg1>
void __f(const char *name, Arg1 &&arg1) {
cout<<name<<" : ";
__p(arg1);
cout<<endl;
}
template<typename Arg1, typename ... Args>
void __f(const char *names, Arg1 &&arg1, Args &&... args) {
int bracket=0,i=0;
for(;; i++)
if(names[i]==','&&bracket==0)
break;
else if(names[i]=='(')
bracket++;
else if(names[i]==')')
bracket--;
const char *comma=names+i;
cout.write(names,comma-names)<<" : ";
__p(arg1);
cout<<" | ";
__f(comma+1,args...);
}
void setIO(string s = "") {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin.exceptions(cin.failbit);
cout.precision(15); cout << fixed;
#ifdef ONLINE_JUDGE
if(sz(s)){
freopen((s+".in").c_str(),"r",stdin);
freopen((s+".out").c_str(),"w",stdout);
}
#define __f(...) 0
#endif
}
const int N = 500 + 1;
bitset<N*N> ans, EMPTY, now, is, can, check;
signed main(){
setIO() ;
int n; rd(n);
vt<int> a(n);
for(auto& i : a) cin >> i;
int total = accumulate(all(a),0);
{
check[0] = true;
for(auto i : a){
check |= check << i;
}
if(total%2 == 1 || !check[total/2]){
cout << 0; exit(0);
}
}
for(int i = 0; i < N*N; ++i){
ans[i] = true;
}
is[0] = true;
for(int i = 0; i < n; ++i){
now = is;
for(int j = i+1; j < n; ++j){
now |= now << a[j];
}
int sum = total - a[i];
can = EMPTY;
for(int i = 0; i < N*N; ++i){
if(now[i]){
int j = abs(2*i - sum);
can[j] = true;
}
}
ans &= can;
is |= is << a[i];
}
cout << int(ans.count()) << endl;
for(int i = 0; i < N*N; ++i){
if(ans[i]) cout << i << ' ' ;
}
}
