#include <bits/stdc++.h>
using namespace std;
int a[15];
vector<pair<int, int> > v;
int main() {
  int n, sum = 0, s = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    sum = sum + a[i];
    v.push_back(make_pair(a[i], i + 1));
  }
  int f = 0;
  if (n == 1) {
    cout << -1 << endl;
    return 0;
  }
  sort(v.begin(), v.end());
  reverse(v.begin(), v.end());
  if (sum % 2 != 0) {
    cout << 1 << endl;
    cout << v[0].second << endl;
  } else {
    sum = sum / 2;
    for (int i = 0; i < n; i++) {
      s = s + v[i].first;
      if (s > sum) {
        f = i;
        break;
      }
    }
    if (f == n - 1) {
      cout << -1 << endl;
      return 0;
    }
    cout << f + 1 << endl;
    for (int i = 0; i <= f; i++) {
      cout << v[i].second << " ";
    }
  }
  return 0;
}
