#include <bits/stdc++.h>
using namespace std;
 
#define fastIO ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
#define endl '\n'
#define lli long long int
#define ld long double
#define p_b push_back
#define m_p make_pair
#define fs first
#define sc second
#define sz(x) ((lli)x.size())
#define all(x) x.begin(),x.end()
const lli mod = 1e9 + 7;
const lli N = 1e6 + 5;
/*****************************************************/
lli t,n,m,a[N]={0},target;
bool dp[105][200005],vis[105][200005];
lli F(lli idx,lli ss)
{
    if(vis[idx][ss])
        return dp[idx][ss];
    vis[idx][ss]=true;
    if(idx>n)
    {
        if(ss==target)
            return dp[idx][ss]=true;
        return dp[idx][ss]=false;
    }
    bool ret=F(idx+1,ss),ret1=F(idx+1,ss+a[idx]);
    if(ret || ret1)
        return dp[idx][ss]=true;
    return dp[idx][ss]=false;
}
int main()
{
    fastIO
    lli i,j,k,x,y;
    lli ss=0;
    cin>>n;
    for(i=1;i<=n;i++)
    {
        cin>>a[i];
        ss+=a[i];
    }
    if(ss%2!=0)
    {
        cout<<"0";
        return 0;
    }
    target=ss/2;
    memset(vis,false,sizeof vis);
    memset(dp,false,sizeof dp);
    if(F(1,0)==false)
    {
        cout<<"0";
        return 0;
    }
    while(1)
    {
        for(i=1;i<=n;i++)
        {
            if(a[i]%2!=0)
            {
                cout<<"1\n"<<i;
                return 0;
            }
            a[i]/=2;
        } 
    }
    
    // cerr<< '\n' << "Time elapsed :" << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n" ;
    return 0;
}