#include <bits/stdc++.h>

#define ll long long
#define pb push_back
#define f first
#define s second
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define ios ios_base::sync_with_stdio(false);cin.tie(NULL)
#define ld long double
#define li __int128

using namespace std;

mt19937 rng(time(NULL));
const int N=1e9;
double r(){
	return (double)(rng()%N)/N;
}
double p(int ol,int ne,double temp){
	if(ne<ol)return 1.0;
	return exp((ol-ne)/temp);
}

int main()
{
	int n;
	scanf("%i",&n);
	vector<bool> in(n);
	int sm=0;
	vector<int> c(n);
	for(int i=0;i<n;i++){
		scanf("%i",&c[i]);
	}
	for(int i=0;i<n/2;i++){
		int x=rng()%n;
		while(in[x])x=rng()%n;
		in[x]=1;
		sm+=c[x];
	}
	double temp=1e9,an=0.999995;
	int treba=1e9;
	while(1){
		int a=rng()%n;
		while(!in[a])a=rng()%n;
		int b=rng()%n;
		while(in[b])b=rng()%n;
		int ns=sm-c[a]+c[b];
		double x=p(abs(treba-sm),abs(treba-ns),temp);
		if(r()<=x){
			in[a]=0;
			in[b]=1;
			sm=ns;
		}
		if(ns==treba){
			printf("%i",n/2);
			for(int i=0;i<n;i++){
				if(in[i]){
					printf(" %i",i+1);
				}
			}
			printf("\n");
			return 0;
		}
		temp=temp*an;
	}
	return 0;
}