#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[100001];
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  int flag;
  if (n > 2) {
    for (int i = 1; i < n; i++) {
      if (a[i] != a[i + 1]) {
        swap(a[i], a[i + 1]);
        flag = 0;
        for (int j = 2; j <= n; j++) {
          if (a[j] > a[j - 1]) {
            flag++;
            break;
          }
        }
        for (int j = 2; j <= n; j++) {
          if (a[j] < a[j - 1]) {
            flag++;
            break;
          }
        }
        swap(a[i], a[i + 1]);
        if (flag < 2) continue;
        cout << i << " " << i + 1 << endl;
        return 0;
      }
    }
    cout << -1 << endl;
  } else
    cout << -1 << endl;
  return 0;
}
