#include <bits/stdc++.h>
using namespace std;
int n;
int arr[100010];
bool sorted() {
  bool sort1 = true, sort2 = true;
  for (int i = 0; i < n - 1; i++) {
    if (arr[i] > arr[i + 1]) sort1 = false;
    if (arr[i] < arr[i + 1]) sort2 = false;
  }
  return sort1 | sort2;
}
int main() {
  cin >> n;
  if (n <= 2) {
    cout << -1 << endl;
    return 0;
  }
  bool flag = true;
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
    if (i > 0 && arr[i] != arr[i - 1]) flag = false;
  }
  if (flag) {
    cout << -1 << endl;
    return 0;
  }
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      if (arr[i] == arr[j]) continue;
      swap(arr[i], arr[j]);
      if (!sorted()) {
        cout << i + 1 << " " << j + 1 << endl;
        return 0;
      }
      swap(arr[i], arr[j]);
    }
  }
  cout << -1 << endl;
}
