#include<bits/stdc++.h>
using namespace std;

bool possible(int *arr, int n)
{
	int s=0;
	s = accumulate(arr,arr+n,s);
	if(s%2)
		return false;
	bitset<2000000> b;
	b[0] = 1;
	for(int i=0;i<n;i++)
		b = b|(b<<arr[i]);
	return b[s/2];
}

int main()
{
	int n;
		cin>>n;
		int arr[n];
		for(int i=0;i<n;i++)
		{
			cin>>arr[i];
		}
		if(possible(arr,n))
		{
			pair<int,int> mn;
			mn = make_pair(__builtin_ctz(arr[0]),1);
			for(int i=1;i<n;i++)
			{
				mn = min(make_pair(__builtin_ctz(arr[i]),i+1),mn);
			}
			cout<<1<<endl<<mn.second<<endl;
		}
		else
		{
			cout<<0<<endl;
		}
	return 0;
}