#include <bits/stdc++.h>
using namespace std;
int a[100005], n;
int main() {
  scanf("%d", &n);
  for (int i = 0; i <= n - 1; ++i) scanf("%d", &a[i]);
  bool ok = true;
  for (int i = 1; i <= n - 1; ++i)
    if (a[i - 1] != a[i]) {
      ok = false;
      break;
    }
  if (ok) {
    printf("-1");
    return 0;
  }
  for (int i = 0; i <= n - 2; ++i)
    for (int j = i + 1; j <= n - 1; ++j)
      if (a[i] != a[j]) {
        swap(a[i], a[j]);
        bool ok;
        if (a[0] >= a[1]) {
          ok = true;
          for (int k = 2; k <= n - 1; ++k)
            if (a[k - 1] < a[k]) {
              ok = false;
              break;
            }
          if (ok) {
            swap(a[i], a[j]);
            continue;
          }
        }
        if (a[0] <= a[1]) {
          ok = true;
          for (int k = 2; k <= n - 1; ++k)
            if (a[k - 1] > a[k]) {
              ok = false;
              break;
            }
          if (ok) {
            swap(a[i], a[j]);
            continue;
          }
        }
        printf("%d %d\n", i + 1, j + 1);
        return 0;
      }
  printf("-1");
  return 0;
}
