#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
	freopen("asm_contribute.in","r",stdin);
	freopen("asm_contribute.out","w",stdout);
	int n,a[1000],ans[10],cnt=0;
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>a[i];
	for(int i=1;i<=n;i++)
	{
		if(a[i]==1)
		{
			ans[++cnt]=i;
		}
	}
	if(cnt%2!=0&&cnt>2)
	{
		cout<<"2"<<endl;
		for(int i=1;i<=2;i++) cout<<ans[i]<<" ";
	}
	else
	{
		cout<<cnt<<endl;
		for(int i=1;i<=cnt;i++)
		{
			cout<<ans[i]<<" ";
		}
	}
	return 0;
}