/**
* Author : Nguyen Tuan Vu
* Created : 27.11.2022
**/
#pragma GCC optimize("O3")
#pragma GCC target("avx,avx2,fma")
#include<bits/stdc++.h>
#define MASK(x) ((1)<<(x))
#define BIT(x, i) (((x)>>(i))&(1))
#define ALL(v) (v).begin(), (v).end()
#define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define db(val) "["#val" = "<<(val)<<"] "
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
template <class X, class Y> bool minimize(X &a, Y b) {
if (a > b) return a = b, true;
return false;
}
template <class X, class Y> bool maximize(X &a, Y b) {
if (a < b) return a = b, true;
return false;
}
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int Rand(int l, int r) {return l + rng() % (r - l + 1);}
void file(){
#define TASK "TASK"
if(fopen(TASK".in", "r")) {
freopen(TASK".in", "r", stdin);
freopen(TASK".out", "w", stdout);
}
}
const int N = 5e2 + 5;
const int M = 5e2 * 5e2;
int n, a[N], b[N];
bitset <2 * M + 5> dp[2];
bitset <2 * M + 5> calc(int n) {
dp[0].reset(); dp[1].reset();
dp[0][M] = 1;
REP(i, n) {
if (dp[i & 1].count() == 0) break;
dp[(i + 1) & 1] |= dp[i & 1] << b[i + 1];
dp[(i + 1) & 1] |= dp[i & 1] >> b[i + 1];
dp[i & 1].reset();
}
return dp[n & 1];
}
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
file();
cin >> n;
FOR(i, 1, n) cin >> a[i], b[i] = a[i];
if (calc(n)[M] == 0) return cout << 0, 0;
bitset <2 * M + 5> tmp;
FOR(i, 0, 2 * M) tmp[i] = 1;
vector <int> ID;
FOR(i, 1, n) ID.push_back(i);
if (n <= 200) {
FOR(i, 1, n) {
int cnt = 0;
FOR(j, 1, n) if (i != j) b[++cnt] = a[j];
tmp &= calc(n - 1);
if (tmp.count() == 0) break;
}
}
else {
FOR(t, 1, n / 4) {
int i = ID[t - 1];
int cnt = 0;
FOR(j, 1, n) if (i != j) b[++cnt] = a[j];
tmp &= calc(n - 1);
if (tmp.count() == 0) break;
}
}
vector <int> ans;
FOR(i, 0, 2 * M) if (tmp[i]) ans.push_back(abs(i - M));
sort (ALL(ans)); ans.erase(unique(ALL(ans)), ans.end());
cout << ans.size() << '\n';
for (auto x : ans) cout << x << ' ';
cerr << "Time elapsed: " << TIME << " s.\n";
return 0;
}
/*
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INPUT: |
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OUTPUT: |
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*/
