#include <bits/stdc++.h>
using namespace std;
#ifndef LOCAL
const int MAXN = 270;
const int MAXA = 270;
const int SZ = MAXN * MAXA + 1;
#else
const int MAXN = 20;
const int MAXA = 20;
const int SZ = MAXN * MAXA + 1;
#endif
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0);
int n;
cin >> n;
vector<int> a(n);
for (auto& el : a)
cin >> el;
auto adddp = [&](const bitset<SZ>& bs, int a) {
bitset<SZ> res;
res = (bs << a) | (bs >> a);
int curi = bs._Find_first();
while (curi < a) {
res[a - curi] = 1;
curi = bs._Find_next(curi);
}
return res;
};
vector<bitset<SZ>> suffdp(n + 1);
suffdp[n][0] = 1;
for (int i = n - 1; i >= 0; --i)
suffdp[i] = adddp(suffdp[i + 1], a[i]);
if (!suffdp[0][0]) {
cout << 0;
return 0;
}
bitset<SZ> ans;
ans.set();
bitset<SZ> cur;
cur[0] = 1;
for (int i = 0; i < n; ++i) {
auto& left = cur;
auto& right = suffdp[i + 1];
bitset<SZ> temp;
int curi = left._Find_first();
while (curi != SZ) {
temp |= (right << curi);
temp |= (right >> curi);
curi = left._Find_next(curi);
}
curi = right._Find_first();
while (curi != SZ) {
temp |= (left << curi);
temp |= (left >> curi);
curi = right._Find_next(curi);
}
ans &= temp;
cur = adddp(cur, a[i]);
}
vector<int> vars;
for (int i = 1; i <= MAXN * MAXA; ++i)
if (ans[i])
vars.push_back(i);
cout << vars.size() << '\n';
for (auto el : vars)
cout << el << ' ';
}
