#include<bits/stdc++.h>
using namespace std;
 
typedef long long ll;
#define  loop(n)        for(ll i=0;i<(n);++i)
#define  rep(i,zz,n)    for(ll i=zz;i<(n);++i)
#define  all(v)         v.begin(),v.end()
#define  pb             push_back
#define  ff             first
#define  ss             second
#define  sz(x)          (int)x.size()
#define  nline          cout<<'\n'
 
const ll mod=1e9+7;
const ll N1=2e5+10;
 
int code(){
    ll n;
    cin>>n;
    vector<ll> a(n);
    ll sum=0;
    loop(n){
        cin>>a[i];
        sum+=a[i];
    }
    if(sum%2){
        cout<<0;
        return 0;
    }
    vector<vector<bool>> dp(n,vector<bool>(sum+1));
    dp[0][0]=dp[0][a[0]]=1;
    rep(i,1,n){
        rep(j,0,sum+1){
            if(dp[i-1][j]){
                dp[i][j]=dp[i][j+a[i]]=1;
            }
        }
    }
    if(dp[n-1][sum/2]){
        cout<<1;nline;
        while(56734){
            rep(i,0,n){
                if(a[i]%2){
                    cout<<i+1;
                    return 0;
                }
                a[i]/=2;
            }
        }
    }
    else    cout<<0;
    return 0;
}
 
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    // freopen("input.txt","r",stdin);
    // freopen("output.txt","w",stdout);
    ll tc=1;
    // cin>>tc;
    loop(tc)  code();
    return 0;
}