#include <bits/stdc++.h>
using namespace std;
const int md = 1e8;
const long long int MAX = 1e5 + 5;
int main() {
  long long int n;
  cin >> n;
  if (n <= 2) {
    cout << -1;
    return 0;
  }
  vector<long long int> vec(n), asc, dec;
  for (int i = 0; i < n; i++) cin >> vec[i];
  asc = vec;
  dec = vec;
  sort(asc.begin(), asc.end());
  sort(dec.rbegin(), dec.rend());
  for (long long int i = n - 1; i >= 0; i--) {
    if (vec[i] == vec[n - 2]) continue;
    swap(vec[n - 2], vec[i]);
    if (vec != asc && vec != dec) {
      cout << n - 1 << " " << i + 1;
      return 0;
    }
    swap(vec[n - 2], vec[i]);
  }
  for (long long int i = 0; i < n; i++) {
    if (vec[i] == vec[1]) continue;
    swap(vec[1], vec[i]);
    if (vec != asc && vec != dec) {
      cout << "2 " << i + 1;
      return 0;
    }
    swap(vec[1], vec[i]);
  }
  cout << -1;
  return 0;
}
