#include<bits/stdc++.h>
#include<fstream>
using namespace std;
#define sz(a) (int)a.size()
#define ALL(v) v.begin(), v.end()
#define ALLR(v) v.rbegin(), v.rend()
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define mpp make_pair
const ld PI = 3.14159265359, prec = 1e-9;;
//using u128 = __uint128_t;
//const int x[4] = {1, 0, -1, 0};
//const int y[4] = {0, -1, 0, 1};
const ll mod = 1e9 + 7, pr = 31;
const int mxn = 3e5 + 5, mxq = 1e5 + 5, sq = 450, mxv = 5e4 + 1;
//const int base = (1 <<18);
const ll inf = 1e18 + 5, neg = -69420, inf2 = 1e14;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
// have fun!
// <3;
int n;
int dp[505 * 505], a[505], cnt[505 * 505];
void add(int &a, int b){
a += b;
if(a >= mod)a -= mod;
}
void sub(int &a, int b){
b = -b + mod;
add(a, b);
}
void addv(int x){
for(int j = 500 * 500; j >= x; j--){
add(dp[j], dp[j - x]);
}
}
void remv(int x){
for(int j = x; j <= 500 * 500; j++){
sub(dp[j], dp[j - x]);
}
}
void solve(){
cin >> n;
int tot = 0;
for(int i = 1; i <= n; i++){
cin >> a[i]; tot += a[i];
}
dp[0] = 1;
for(int i = 1; i <= n; i++){
addv(a[i]);
}
if((tot & 1) || !dp[tot / 2]){
cout << 0; return;
}
for(int i = 1; i <= n; i++){
remv(a[i]);
tot -= a[i];
for(int j = 0; j <= tot / 2; j++){
if(dp[j]){
cnt[tot - 2 * j]++;
}
}
addv(a[i]);
tot += a[i];
}
vt<int>res;
for(int i = 1; i <= tot; i++){
if(cnt[i] == n)res.pb(i);
}
cout << sz(res) << "\n";
for(auto i: res)cout << i << " ";
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//freopen("netw.inp", "r", stdin);
//freopen("netw.out", "w", stdout)
int tt; tt = 1;
while(tt--){
solve();
}
return(0);
}
