#include <bits/stdc++.h>
using namespace std;
const int N = 100000 + 100;
int n, a[N];
inline bool issorted() {
  bool x = 1, y = 1;
  for (int i = 0; i < n - 1; i++)
    if (a[i] > a[i + 1]) {
      x = 0;
      break;
    }
  for (int i = n - 1; i > 0; i--)
    if (a[i] > a[i - 1]) {
      y = 0;
      break;
    }
  return x | y;
}
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", a + i);
  if (n == 2) {
    printf("-1\n");
    return 0;
  }
  bool dif = 0;
  for (int i = 0; i < n - 1; i++)
    if (a[i] != a[i + 1]) {
      dif = 1;
      break;
    }
  if (!dif) {
    printf("-1\n");
    return 0;
  }
  for (int i = 0; i < n; i++)
    for (int j = i + 1; j < n; j++)
      if (a[i] != a[j]) {
        swap(a[i], a[j]);
        if (!issorted()) {
          printf("%d %d\n", i + 1, j + 1);
          return 0;
        }
        swap(a[i], a[j]);
      }
  printf("-1\n");
  return 0;
}
