#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a;
  cin >> n;
  vector<pair<int, int> > v;
  for (int i = 1; i <= n; i++) {
    cin >> a;
    v.push_back(make_pair(a, i));
  }
  if (v.size() == 1) {
    cout << -1;
    return 0;
  }
  sort(v.begin(), v.end());
  int s1 = v[0].first, s2 = 0;
  for (int i = 1; i < v.size(); i++) {
    s2 += v[i].first;
  }
  if (s2 == s1)
    cout << -1;
  else
    cout << "1\n" << v[0].second;
  return 0;
}
