#include<bits/stdc++.h>
using namespace std;
#define ll long long
ll ss[200005][2];
int main()
{
    ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    ll t;
    t=1;
    for(ll test=0;test<t;test++)
    {
        ll n;
        cin>>n;
        ll a[n];
        for(ll i=0;i<n;i++)
        {
            cin>>a[i];
        }
        ss[0][0] = 1;
        for(ll i=0;i<n;i++)
        {
            for(ll j=0;j<a[i];j++)
            {
                ss[j][1-i%2] = ss[j][i%2];
            }
            for(ll j=a[i];j<=200000;j++)
            {
                ss[j][1-i%2] = ss[j][i%2]|ss[j-a[i]][i%2];
            }
        }
        ll it = 0;
        while(1)
        {
            it++;
            ll sum = 0;
            ll flag = 0;
            for(ll i=0;i<n;i++)
            {
                sum+=a[i];
                if(a[i]%2!=0)
                {
                    flag = i+1;
                }
            }
            ll tt = sum/2;
            if((sum%2==1)||((!ss[tt][n%2])&&(it==1)))
            {
                cout<<0<<"\n";
                break;
            }
            else
            {
                if(flag>0)
                {
                    cout<<1<<"\n"<<flag<<"\n";
                    break;
                }
                else
                {
                    for(ll i=0;i<n;i++)
                    {
                        a[i]/=2;
                    }
                }
            }
        }
    }
}
