#include <bits/stdc++.h>

using namespace std;

const int maxn=105;
const int mod=3e6+19;
const int ed=1e9;
int a[maxn];
bitset<mod> b[maxn];
vector<int> res;

int main(){
	
	mt19937 rnd(time(0));
	
	int n;
	
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%d",&a[i]);
	
	b[0][0]=1;
	
	for(int i=1;i<=n;i++){
		b[i]=b[i-1]|(b[i-1]<<(a[i]%mod));
		if(a[i]%mod) b[i]=b[i]|(b[i-1]>>(mod-(a[i]%mod)));
		// for(int j=0;j<mod;j++){
			// if(b[i][j]) printf("%d ",j);
		// }
		// puts("");
	}
	
	while(1){
		int now=(ed%mod);
		res.clear();
		for(int i=n;i>=1;i--){
			if(b[i-1][now]&&b[i-1][(now-(a[i]%mod)+mod)%mod]&&(rnd()&1)){
				res.push_back(i);
				now=(now-(a[i]%mod)+mod)%mod;
			}else if(b[i-1][(now-(a[i]%mod)+mod)%mod]){
				res.push_back(i);
				now=(now-(a[i]%mod)+mod)%mod;
			}
		}
		int sum=0;
		for(int x : res) sum+=a[x];
		if(sum==1e9){
			printf("%d ",(int)res.size());
			for(int x : res) printf("%d ",x);
			puts("");
			return 0;
		}
	}
	
	return 0;
}