#include <bits/stdc++.h>
using namespace std;
const long long int mod = 1e9 + 9;
const long long int mod2 = 1e9 + 9;
const long long int maxn = 2e6 + 5;
const long long int maxn1 = 1e7 + 1;
const int root = 1e6 + 5;
const long long inf = 1e18 + 18;
double pie4 = 3.1415926535;
pair<long long int, long long int> a[20];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int n, i, total = 0, sum = 0, left = 0, idx = -1;
  cin >> n;
  for (i = 1; i <= n; i++) {
    cin >> a[i].first;
    total += a[i].first;
    a[i].second = i;
  }
  sort(a + 1, a + n + 1);
  for (i = 1; i <= n; i++) {
    sum += a[i].first;
    left = total - sum;
    if (left == 0) continue;
    if (sum != left) {
      idx = i;
      break;
    }
  }
  if (idx == -1)
    cout << idx << endl;
  else {
    cout << idx << endl;
    for (i = 1; i <= idx; i++) cout << a[i].second << " ";
  }
}
