//頑張って
#include <bits/stdc++.h>
#define ff first
#define ss second
#define ll long long
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;
#define all(x) x.begin(), x.end()
void solve() {
   int n;
   cin >> n;
   vector <int> a(n);
   for (auto &i : a)
      cin >> i;
   int mxn = accumulate(all(a), 0);
   vector <bool> dp(mxn + 1);
   dp[0] = true;
   for (int i = 0; i < n; i++) {
      for (int j = mxn - a[i]; j >= 0; j--) {
         if (dp[j] == true)
            dp[a[i] + j] = true;
      }
   }
   if ((mxn % 2 == 0 && !dp[mxn / 2]) || mxn % 2) {
      cout << "0\n";
      return;
   }
   while (true) {
      for (int i = 0; i < n; i++) {
         if (a[i] % 2 != 0) {
            cout << "1\n" << i + 1 << '\n';
            return;
         }
         a[i] /= 2;
      }
   }
}
int main() {
#ifndef ONLINE_JUDGE
   freopen("inp.in", "r", stdin);      freopen("outp.in", "w", stdout);
#endif
   ios::sync_with_stdio(false);   cin.tie(NULL);   cout.tie(NULL);
   solve();
   return 0;
}