#include <bits/stdc++.h>
using namespace std;
int a[100005];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  for (int i = 1; i < n; i++) {
    if (a[i] != a[i - 1]) {
      swap(a[i], a[i - 1]);
      int cnt1 = n - 1, cnt2 = n - 1;
      for (int j = 1; j < n; j++) {
        if (a[j] <= a[j - 1]) cnt1--;
        if (a[j] >= a[j - 1]) cnt2--;
      }
      if (cnt1 && cnt2) {
        cout << i << " " << i + 1 << endl;
        return 0;
      }
      swap(a[i], a[i - 1]);
    }
  }
  cout << -1 << endl;
  return 0;
}
