#include <bits/stdc++.h>
using namespace std;
#define int long long
#define sp << ' ' <<
#define nl << '\n'
const int LIM = 500 * 500;
int n, dp[LIM + 1] = {1}, possible[LIM + 1];
signed main(){
cin.tie(0)->sync_with_stdio(0);
cin >> n;
int a[n]; for(int &i : a) cin >> i;
int sum = accumulate(a, a+n, 0LL);
for(int &i : a){
for(int j=LIM; j>=i; --j) dp[j] += dp[j-i];
}
bool ok = false;
for(int i=0; i<LIM; ++i) if(dp[i] && i+i == sum) ok = true;
if(!ok){
cout << 0;
return 0;
}
for(int i : a){
int c[LIM + 1];
for(int j=0; j<=LIM; ++j) c[j] = dp[j];
for(int j=i; j<=LIM; ++j) c[j] -= c[j-i];
for(int j=0; j<=LIM; ++j){
if(!c[j]) continue;
int k = 2 * j + i - sum;
if(0<=k && k<=LIM) ++possible[k];
}
}
vector<int> ans;
for(int i=0; i<=LIM; ++i) if(possible[i] == n) ans.push_back(i);
cout << ans.size() nl;
for(int i : ans) cout << i << ' ';
}
