#include <bits/stdc++.h>
#define ll long long
#define lint long long
#define IOS std::ios::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);
using namespace std;
lint equalPartition(lint N, lint arr[])
    {
        // code here
        lint sum=0;
        for(int i=0;i<N;i++) sum+=arr[i];
        if(sum%2) return 0;
        sum/=2;
        lint dp[sum+2];
        dp[0]=1;
        for(lint i=1;i<=sum;i++) dp[i]=0;
        
        for(lint i=1;i<=N;i++)
        {
            for(lint j=sum;j>0;j--)
            {
                if((j-arr[i-1])>=0 && !dp[j]) dp[j]=dp[j-arr[i-1]];
            }
        }
        return dp[sum];
    }

int main(){
	IOS;
	ll n;
	cin >> n;
	ll arr[n];
	ll sum = 0;
	ll odd = 0;
	ll count4 = 0;
	for(ll i = 0;i<n;i++){
		cin >> arr[i];
		sum += arr[i];
		if(arr[i]%2 != 0)odd++;
		if(arr[i]%4 == 0)count4++;
	}
	if(sum%2)cout << "0\n";
	else{
		if(!equalPartition(n,arr))cout << "0\n";
		else{
			if(odd > 0){
				cout << "1\n";
				for(ll i = 0;i<n;i++){
					if(arr[i]%2 != 0){
						cout <<  i+1 << "\n";
						break;
					}
				}
			}
			else{
				
				
				cout << 1 << "\n";
				for(lint i = 0;i<n;i++){
					lint arr1[n-1];
					lint k = 0;
					for(lint j = 0;j<n-1;j++){
						if(j<i)arr1[j] = arr[j];
						if(j >= i)arr1[j] = arr[j+1];
					
					}
					if(!equalPartition(n-1,arr1)){
						cout << i+1 << "\n";
						break;
					}
					
				}
				
			}
		}
	}
	return 0;
}
