#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,bmi,bmi2,lzcnt,popcnt")
const int S = (500 * 500) + 1;
const int S2 = (500 * 500) / 2 + 1;
bitset<S> bs[501];
bitset<S2> bs2;
int main() {
ios_base::sync_with_stdio(false);
cout.tie(0); cin.tie(0);
int n, sum = 0;
cin >> n;
vector<int> v(n);
bs2[0] = 1;
for(int &x : v) {
cin >> x;
sum += x;
bs2 |= (bs2 << x);
}
if(sum % 2 == 1 || !bs2[sum/2]) {
cout << 0 << '\n';
return 0;
}
for(int i=0; i<n; i++) {
bs[i+1][0] = 1;
for(int j=0; j<n; j++)
if(i != j) bs[i+1] |= (bs[i+1] << v[j]);
}
vector<int> ans;
for(int j=1; j<min(sum, S); j++) {
bool ok = 1;
for(int i=1; i<=n; i++) {
if( (sum - v[i-1] + j) % 2 == 1 ) {
ok = 0;
break;
}
if( (bs[i][(sum - v[i-1] + j) / 2]) == 0) {
ok = 0;
break;
}
}
if(ok) ans.push_back(j);
}
cout << ans.size() << '\n';
for(int &x : ans) cout << x << " ";
return 0;
}
