#include <bits/stdc++.h>
#define fo(i, d, c) for (int i = d; i <= c; i++)
#define fod(i, c, d) for (int i = c; i >= d; i--)
#define maxn 1000010
#define N 1010
#define fi first
#define se second
#define pb emplace_back
#define en cout << "\n";
#define bitcount(x) __builtin_popcountll(x)
#define pii pair<int, int>
#define vii vector<pii>
#define lb(x) x & -x
#define bit(i, j) ((i >> j) & 1)
#define offbit(i, j) (i ^ (1LL << j))
#define onbit(i, j) (i | (1LL << j))
#define vi vector<int>
#define all(x) x.begin(), x.end()
#define ss(x) (int)x.size()
template <typename T1, typename T2>
bool minimize(T1 &a, T2 b)
{
if (a > b)
{
a = b;
return true;
}
return false;
}
template <typename T1, typename T2>
bool maximize(T1 &a, T2 b)
{
if (a < b)
{
a = b;
return true;
}
return false;
}
using namespace std;
const int nsqrt = 450;
const int mod = 1e9 + 7;
void add(int &x, int k)
{
x += k;
x %= mod;
if(x < 0) x += mod;
}
void del(int &x, int k)
{
x -= k;
x %= mod;
if(x < 0) x += mod;
}
const int nn = 250001;
int n,a[555];
bitset<nn> p[502],s[502];
main()
{
#define name "TASK"
if (fopen(name ".inp", "r"))
{
freopen(name ".inp", "r", stdin);
freopen(name ".out", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
fo(i,1,n) cin >> a[i];
int tot = 0;
bitset<nn> checker;
checker[0] = 1;
fo(i,1,n)
{
checker |= checker << a[i];
tot += a[i];
}
if(tot % 2 == 1 or checker[tot / 2] == 0) return cout << 0,0;
p[0][0] = s[n + 1][0] = 1;
fo(i,1,n)
{
p[i] = p[i - 1];
p[i] |= p[i] << a[i];
}
fod(i,n,1)
{
s[i] = s[i + 1];
s[i] |= s[i] << a[i];
}
bitset<nn> odd,even,cur;
even.set();
odd.set();
even[0] = 0;
fo(i,1,n)
{
if(i > n / 2)
{
cur = p[i - 1];
fo(j,i + 1,n) cur |= cur << a[j];
}
else
{
cur = s[i + 1];
fod(j,i - 1,0) cur |= cur << a[j];
}
int tot1 = tot - a[i];
if(tot1 % 2 == 0)
{
odd &= 0;
even &= cur >> (tot1 / 2);
}
else
{
even &= 0;
odd &= cur >> ((tot1 + 1) / 2);
}
}
cout << even.count() + odd.count();en;
fo(i,1,tot / 2) if(even[i]) cout << i * 2 << ' ';
fo(i,0,(tot + 1) / 2) if(odd[i]) cout << i * 2 + 1 << ' ';
}
