#include <fstream>
#define N 201
using namespace std;
typedef long long ll;
int n;
ll o[N]={0};
bool l[N]={0};
ifstream in("asm_contribute.in");
ofstream out("asm_contribute.out");
int main()
{
	int i,j;
	ll temp,solo=0;
	int cnt=0,bnt=0;
	in>>n;
	for(i=1;i<=n;i++)in>>o[i];
	//for(i=1;i<=n;i++)out<<o[i]<<endl;
	for(i=1;i<(1<<n);i++)
	{
		cnt=bnt=solo=0;
		temp=i;
		for(j=1;j<=n;j++)l[j]=0;
		while(temp)
		{
			l[++cnt]=temp%2;
			temp=temp>>1;
		}
		//out<<endl;
		//for(j=1;j<=n;j++)out<<l[j]<<' ';
		//out<<endl;
		for(j=1;j<=n;j++)
		{
			if(l[j])
			{
			    solo^=o[j];
				bnt++;
			}
		}
		if(solo==0)
		{
			out<<bnt<<endl;
			for(j=1;j<=n;j++)
			if(l[j])out<<j<<' ';
			break;
		}
	}
	return 0;
}