#include <bits/stdc++.h>
using namespace std;
const int N = 5e5 + 229;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  map<int, int> nom;
  int n, s = 0;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    s += a[i];
    nom[a[i]] = i;
  }
  sort(a, a + n);
  if (n > 1 && a[0] != s - a[0]) {
    cout << 1 << endl << nom[a[0]] + 1;
  } else {
    cout << -1;
  }
  return 0;
}
