#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair <ll,ll> pll;
typedef pair <int,int> pii;
typedef pair <int,pii> piii;
#define forr(_a,_b,_c) for(int _a = (_b); _a <= (_c); ++_a)
#define ford(_a,_b,_c) for(int _a = (_b) + 1; _a --> (_c);)
#define forf(_a,_b,_c) for(int _a = (_b); _a < (_c); ++_a)
#define st first
#define nd second
#define pb push_back
#define mp make_pair
#define all(x) begin(x),end(x)
#define mask(i) (1LL << (i))
#define bit(x, i) (((x) >> (i)) & 1)
#define bp __builtin_popcountll
#define file "test"
const int N = 5e2 + 5;
const ll oo = 1e9;
const ll mod = 1e9 + 7;
const int lmt = 250001;
bitset <lmt> res, pre[N], suf[N], tmp;
int n, a[N], sum, cnt[4];
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef hqm
freopen(file".inp", "r", stdin); freopen(file".out", "w", stdout);
#endif
cin >> n;
forr (i, 1, n)
cin >> a[i], sum += a[i], cnt[a[i] & 1]++;
pre[0][0] = 1;
suf[n + 1][0] = 1;
forr (i, 1, n) pre[i] = pre[i - 1] | (pre[i - 1] << a[i]);
ford (i, n, 1) suf[i] = suf[i + 1] | (suf[i + 1] << a[i]);
if (sum % 2 || !pre[n][sum / 2] || min(cnt[0], cnt[1]) > 0){
cout << 0;
return 0;
}
res.set();
forr (i, 1, n){
if (i * 2 <= n){
tmp = suf[i + 1];
ford (j, i - 1, 1)
tmp |= tmp << a[j];
}
else {
tmp = pre[i - 1];
forr (j, i + 1, n)
tmp |= tmp << a[j];
}
int nsum = sum - a[i];
if (cnt[0])
res &= tmp >> (nsum / 2);
else res &= tmp >> (nsum / 2 + 1);
}
if (cnt[0])
res[0] = 0;
cout << res.count() << "\n";
forf (i, 0, lmt){
if (res[i])
cout << i * 2 + (cnt[1] != 0) << " ";
}
return 0;
}
/*
*/
