#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  long long n;
  cin >> n;
  long long arr[n];
  long long s = 0;
  for (long long i = 0; i < n; i++) {
    cin >> arr[i];
    s += arr[i];
  }
  if (n == 1) {
    cout << -1;
    return 0;
  }
  long long t = 0;
  long long i = 0;
  for (; i < n - 1; i++) {
    t += arr[i];
    if (s - t != t) {
      cout << i + 1 << "\n";
      for (long long j = 0; j <= i; j++) cout << j + 1 << " ";
      return 0;
    }
  }
  if (i == n - 1) cout << -1;
  return 0;
}
