/*
ID: varunra2
LANG: C++
TASK: bootfall
*/
#include<bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif
#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second
const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define trav(a, x) for(auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions
#define N 502
#define siz N * N + 1
int n;
int main() {
// #ifndef ONLINE_JUDGE
// freopen("bootfall.in", "r", stdin);
// freopen("bootfall.out", "w", stdout);
// #endif
cin.sync_with_stdio(0); cin.tie(0);
cin >> n;
VI vals(n);
for(int i = 0; i < n; i++) {
cin >> vals[i];
}
int sm = accumulate(all(vals), 0);
VI cur(siz, 0), prv(siz, 0);
cur[0] = prv[0] = 1;
for(int i = 0; i < n; i++) {
for(int j = vals[i]; j < siz; j++) {
cur[j] += prv[j - vals[i]];
}
prv = cur;
}
bitset<siz> ret;
bitset<siz> each;
if(sm&1 or cur[sm/2] == 0) {
cout << "0\n";
return 0;
}
VI a;
ret.set();
for(int i = 0; i < n; i++) {
sm -= vals[i];
a = cur;
each.reset();
// undo
for(int ii = vals[i]; ii < siz; ii++) {
if(a[ii]) a[ii] -= a[ii - vals[i]];
}
for(int ii = 0; ii <= sm; ii++) {
if(a[ii]) {
int l, r;
l = ii;
r = sm - l;
each[abs(r - l)] = 1;
}
}
ret &= each;
sm += vals[i];
}
cout << ret.count() << '\n';
for(int i = 0; i < siz; i++) {
if(ret[i]) cout << i << " ";
}
cout << '\n';
return 0;
}
