#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef __float128 ld;

#define pii pair<int, int>
#define fi first
#define se second
#define VI vector<int>
#define VII vector<vector<int> >

mt19937 rnd(time(0));

const int N = 500500;
const int inf = 1e9 + 100;
const ll infll = 2e18 + 500;

int a[N], vis[N];

double get_rnd() {
	return 1.0 * rnd() / inf;
}

int main() {
    freopen("1.in", "r", stdin);
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i <= n / 2; i++) vis[i] = 1;
    int s = 0;
    for (int i = 1; i <= n / 2; i++) s += a[i];
    for (int i = n / 2 + 1; i <= n; i++) s -= a[i];
    int ps = 0;
    int asdf = 0;
    while (1) {
    	if (!s) break;
    	asdf++;
    	ps++;
    	double opt = 1e18;
    	int optu = -1, optv = -1;
    	for (int i = 1; i <= n; i++) {
    		int ss = s + a[i] * (vis[i] == 0 ? 2 : -2);
    		double score = abs(ss) * (1 / (get_rnd() + 0));
    		if (score < opt) {
                opt = score;
                optu = i, optv = -1;
    		}
		}
    	for (int i = 1; i <= n; i++) if (vis[i] == 0) for (int j = 1; j <= n; j++) if (vis[j] == 1) {
    		int ss = s + 2 * a[i] - 2 * a[j];
    		double score = abs(ss) * (1 / (get_rnd() + 0));
    		if (score < opt) {
                opt = score;
                optu = i, optv = -1;
    		}
    	}
    	if (optu > 0) {
    		s += a[optu] * (vis[optu] == 0 ? 2 : -2);
    		vis[optu] ^= 1;
    	}
    	if (optv > 0) {
    		s += a[optv] * (vis[optv] == 0 ? 2 : -2);
    		vis[optv] ^= 1;
    	}
    }
    cerr << asdf << endl;
    vector<int> ans;
    for (int i = 1; i <= n; i++) if (vis[i]) ans.push_back(i);
    cout << ans.size() << ' ';
    for (auto e : ans) {
    	cout << e << ' ';
    }
    cout << '\n';

    return 0;
}