#include <fstream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#define ifs ifstream
#define ofs ofstream
#define MAX 10010
using namespace std;
typedef long long ll;
ifs fin("asm_contribute.in");
ofs fout("asm_contribute.out");
ll a[MAX],ans[MAX];
int n;
int read()
{
	fin>>n;
	for(int i=1;i<=n;i++)
		fin>>a[i];
	return 0;
}
int work()//暴力出奇迹（啦啦啦）
{
	for(int k=1;k<=n;k++)
	{
		ans[k]=ans[k-1]^a[k];
		for(int i=k+1;i<=n;i++)
		{
			if((a[i]^ans[k])==0)
			{
				fout<<k+1<<endl;
				for(int j=1;j<=k;j++)
				{
					fout<<j<<' ';
				}fout<<i<<endl;
				return 0;
			}
		}
	}
	return 0;
}
int main()
{
	read();
	work();
	return 0;
}