#include <iostream>
#include <unordered_map>
#include <list>
#include <queue>
#include <string.h>
#include <stack>
#include <set>
#include <unordered_set>
#include <map>
#include <climits>
#include <algorithm>
#include <math.h>
#include <vector>
#include <iomanip>
#include <ctype.h>
using namespace std;
#define ll long long int
const int MOD = 1e9 + 7;
ll facto[200010];
void fact()
{
    facto[0] = 1;
    for (ll i = 1; i < 200010; i++)
    {
        facto[i] = (i * facto[i - 1]) % MOD;
    }
}
bool is(ll cnt[])
{
    for (int i = 0; i < 26; i++)
    {
        if (cnt[i] >= 2)
            return false;
    }
    return true;
}
int main()
{
    // fact();
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll n;
    cin >> n;
    ll a[n];
    ll sum = 0;
    for (ll i = 0; i < n; i++)
    {
        cin >> a[i];
        sum += a[i];
    }
    if ((sum % 2) != 0)
    {
        cout << "0 \n";
        return 0;
    }
    bool dp[n + 1][sum / 2 + 1];
    for (ll i = 0; i <= n; i++)
    {
        for (ll j = 0; j <= sum / 2; j++)
        {
            dp[i][j] = false;
        }
    }
    for (ll i = 0; i <= n; i++)
    {
        dp[i][0] = true;
    }
    for (ll j = 0; j <= sum / 2; j++)
    {
        dp[0][j] = false;
    }
    for (ll i = 1; i <= n; i++)
    {
        for (ll j = 1; j <= sum / 2; j++)
        {
            dp[i][j] = dp[i - 1][j];
            if (j - a[i - 1] >= 0)
            {
                dp[i][j] = dp[i][j] || dp[i - 1][j - a[i - 1]];
            }
        }
    }
    if (dp[n][sum / 2] == false)
    {
        cout << "0 \n";
        return 0;
    }
    ll mini = LLONG_MAX;
    ll pos = -1;
    for (ll i = 0; i < n; i++)
    {
        if (a[i] % 2)
        {
            cout << "1 \n";
            cout << i + 1 << "\n";
            return 0;
        }
    }
    for (ll i = 0; i < n; i++)
    {
        ll steps = 0;
        while (a[i] % 2 == 0)
        {
            a[i] /= 2;
            steps++;
        }
        if (mini > steps)
        {
            mini = steps;
            pos = i;
        }
    }
    cout << "1 \n";
    cout << pos + 1 << "\n";
}
