#include <bits/stdc++.h>
using namespace std;
long long a, arr[1000000];
bool ay7aga2() {
  for (int i = 0; i < a - 1; i++) {
    if (!(arr[i] <= arr[i + 1])) {
      return false;
    }
  }
  return true;
}
bool ay7aga() {
  for (int i = 0; i < a - 1; i++) {
    if (!(arr[i] >= arr[i + 1])) return ay7aga2();
  }
  return true;
}
int main() {
  long long b = 0;
  cin >> a;
  for (int i = 0; i < a; i++) {
    cin >> arr[i];
    if (i != 0 && arr[i - 1] == arr[i]) {
      b++;
    }
  }
  if (b == a - 1 || a <= 2) {
    cout << "-1" << endl;
    return 0;
  }
  for (int i = 0; i < a - 1; i++) {
    for (int j = i + 1; j < a; j++) {
      if (arr[i] != arr[j]) {
        swap(arr[i], arr[j]);
        if (ay7aga() == false) {
          cout << i + 1 << " " << j + 1 << endl;
          return 0;
        } else {
          swap(arr[i], arr[j]);
        }
      }
    }
  }
  cout << "-1" << endl;
  return 0;
}
