#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <cstring>
#include <map>
#include <cstdlib>
#include <ctime>
#include <cassert>
#include <bitset>
#define f first
#define s second
#define ll long long
#define ull unsigned long long
#define mp make_pair
#define pb push_back
#define vi vector <int>
#define ld long double
#define pii pair<int, int>
#define y1 sda
using namespace std;
const int N = 502, mod1 = int(1e9)  + 7, mod2 = int(1e9) + 9;

int n,a[N];

int s, sum;

int dp[N * N];
int f[N * N];
vi ans;
bool used[N];

inline void add(int x){
	for(int j = sum; j >= 0; j--){
		dp[j + x] += dp[j];
		if(dp[j + x] >= mod1) dp[j + x] -= mod1;
	}
	sum += x;
}

inline void del(int x){
	sum -= x;
	for(int j = 0; j <= sum; j++){
		dp[j + x] += (mod1 - dp[j]);
		if(dp[j + x] >= mod1) dp[j + x] -= mod1;
	}
}

int main () {
    freopen("bootfall.in","r", stdin);
    freopen("bootfall.out","w", stdout);
	scanf("%d",&n);
	bool odd = 0, even = 0;
	for(int i = 1; i <= n; i++){
		scanf("%d",&a[i]);
		s += a[i];
		if(a[i] & 1) odd = 1;
		else even = 1;
	}
	if(odd && even){
		printf("0");
		return 0;
	}
	dp[0] = 1;
	for(int i = 1; i <= n; i++){
		add(a[i]);
	}
	if((s & 1) || !dp[s>>1]){
		printf("0");
		return 0;
	}
	for(int i = 1; i <= n; i++){
		if(used[a[i]]) continue;
		used[a[i]] = 1;
		del(a[i]);
		for(int j = 1; j <= s; j++){
			int cur = s - a[i] + j;
			if((cur & 1) || !dp[cur>>1]){
				f[j] = 1;
			}
		}
		add(a[i]);
	}
	for(int x = 1; x <= s; x++){
		if(!f[x]) ans.pb(x);
	}
	printf("%d\n", int(ans.size()));
	for(int i = 0; i < ans.size(); i++){
		printf("%d ", ans[i]);
	}

return 0;
}