/*
DEATH-MATCH
Davit-Marg
*/
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cassert>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <iterator>
#include <ctype.h>
#include <stdlib.h>
#include <fstream>
#define mod 1000000007ll
#define LL long long
#define LD long double
#define MP make_pair
#define PB push_back
using namespace std;
LL n,a[5000006],cant[5000006];
LL sum,sm;
vector<LL> ans;
LL dp[5000006];
void add(LL k)
{
sum += k;
for (LL j = sum; j >= 0; j--)
dp[j + k] += dp[j];
}
void rem(LL k)
{
for (LL i = 0; i <= sum; i++)
dp[i + k] -= dp[i];
sum -= k;
}
int main()
{
cin >> n;
for (LL i = 0; i < n; i++)
{
cin >> a[i];
sm += a[i];
}
dp[0] = 1ll;
for (LL i = 0; i < n; i++)
add(a[i]);
if (sm % 2==1 || dp[sm / 2] == 0)
{
cout << 0 << endl;
return 0;
}
for (LL i = 0; i < n; i++)
{
for (LL j = 0; j <= sm; j++)
{
//assert(dp[(sum + j) / 2]<0);
if ((sum + j) % 2 == 1 || dp[(sum + j) / 2 - j] == 0)
cant[j] = 1;
}
}
for (LL j = 0; j <= sm; j++)
if (!cant[j])
ans.PB(j);
cout << ans.size() << endl;
for (LL i = 0; i < ans.size(); i++)
cout << ans[i] << " ";
cout << endl;
return 0;
}
