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