#include <bits/stdc++.h>
using namespace std;
int n, a[15], sum;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    sum += a[i];
  }
  if (n == 1 || (n == 2 && a[0] == a[1]))
    cout << "-1" << endl;
  else {
    if (sum - a[0] != a[0])
      cout << 1 << endl << 1 << endl;
    else
      cout << 2 << endl << 1 << " " << 2 << endl;
  }
  return 0;
}
