#include<bits/stdc++.h>
#define ll long long int
using namespace std;

int t;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    cin >> n;
    int sum=0;
    int odd=-1;
    vector<int> a(n);
    for (int q=0;q<n;q++){
        int x;
        cin>>x;
        a[q]=x;
        sum+=x;
        if (odd==-1 && x%2==1){
            odd=q;
        }
    }
    if (sum%2==1){
        cout<<0<<"\n";
    }else{
        int s=sum/2;
        bool dp[n+1][s+1];
        for (int i=0;i<=n;i++){
            dp[i][0]=true;
        }
        for (int j=1;j<=s;j++){
            dp[0][j]=false;
        }
        for (int i=1;i<=n;i++){
            for (int j=1;j<=s;j++){
                if (dp[i-1][j]==true){
                    dp[i][j]=true;
                }else{
                    if (a[i-1]>j){
                        dp[i][j]=false;
                    }else{
                        dp[i][j]=dp[i-1][j-a[i-1]];
                    }
                }
            }
        }
        if (dp[n][s]==false){
            cout<<0<<"\n";
        }else{
            if (odd!=-1){
                cout<<1<<"\n";
                cout<<odd+1<<"\n";
            }else{
                int idx=-1;
                int mn=33;
                for (int i=0;i<n;i++){
                    if (mn > __builtin_ctz(a[i])){
                        mn=__builtin_ctz(a[i]);
                        idx=i;
                    }
                }
                cout<<1<<"\n";
                cout<<idx+1<<"\n";
            }
        }
    }
    
}