#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FASTIO ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define pii pair<int, int>
#define ff first
#define ss second
#define PI acos(-1)
#define ld long double
const int mod = 1e9+7, N = 505;
int msb(int val){return sizeof(int)*8-__builtin_clzll(val);}
int a[N], n, m, k;
int dp[N*N], can[N*N];
int sum;
void add(int v){
for(int i=sum;i>=0;i--)dp[i+v] += dp[i];
sum += v;
}
void del(int v){
sum -= v;
for(int i=0;i<=sum;i++)dp[i+v] -= dp[i];
}
void solve(int test_case){
int i, j;
dp[0] = 1;
cin >> n;
for(i=0;i<n;i++){
cin >> a[i];
add(a[i]);
}
if(sum%2!=0 || !dp[sum/2]){
cout << 0 << '\n';
return;
}
for(i=0;i<n;i++){
del(a[i]);
for(j=1;j<=250000;j++){
if((sum+j)%2 || !dp[(sum+j)/2])can[j] = 1;
}add(a[i]);
}
vector<int> ans;
for(i=1;i<=250000;i++)if(!can[i])ans.pb(i);
cout << ans.size() << '\n';
for(auto x : ans)cout <<x<< ' ';
cout << '\n';
return;
}
signed main(){
FASTIO;
#define MULTITEST 0
#if MULTITEST
int ___T;
cin >> ___T;
for(int T_CASE = 1; T_CASE <= ___T; T_CASE++)
solve(T_CASE);
#else
solve(1);
#endif
return 0;
}
