#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]);
	}
	while(1){
		fill(all(in),0);
		sm=0;
		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=0.99999;
		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;
			if(temp<1e-8)break;
		}
	}
	return 0;
}