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