#include <bits/stdc++.h>
using namespace std;
bool issorted(long long int *arr, int n) {
  int flag = 0;
  for (int i = 1; i < n; i++) {
    if (arr[i - 1] > arr[i]) {
      flag = 1;
      break;
    }
  }
  if (flag == 0) return true;
  flag = 0;
  for (int i = n - 2; i >= 0; i--) {
    if (arr[i + 1] > arr[i]) {
      flag = 1;
      break;
    }
  }
  if (flag == 0) return true;
  return false;
}
int main(void) {
  int n;
  cin >> n;
  long long int arr[n];
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  long long int flag = 0;
  for (int i = 1; i < n; i++) {
    if (arr[i] != arr[i - 1]) {
      flag = 1;
      break;
    }
  }
  if (flag == 0 || n <= 2)
    cout << "-1" << endl;
  else if (n == 3 && arr[0] == arr[2])
    cout << "-1" << endl;
  else {
    flag = 0;
    for (int i = 1; i < n; i++) {
      if (arr[i] != arr[i - 1]) {
        long long int swap = arr[i];
        arr[i] = arr[i - 1];
        arr[i - 1] = swap;
        if (!issorted(arr, n)) {
          cout << i + 1 << " " << i << endl;
          break;
        } else {
          swap = arr[i];
          arr[i] = arr[i - 1];
          arr[i - 1] = swap;
        }
      }
    }
  }
}
