#include <bits/stdc++.h>
using namespace std;
const int MOD(1000000007);
const int INF((1 << 30) - 1);
const int MAXN(100005);
int n, a[MAXN], b[MAXN], d[MAXN];
bool unsort() {
  bool c1 = 0, c2 = 0;
  for (int i = 0; i < n; i++)
    if (a[i] != b[i]) {
      c1 = 1;
      break;
    }
  for (int i = 0; i < n; i++)
    if (a[i] != d[i]) {
      c2 = 1;
      break;
    }
  return (c1 & c2);
}
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  if (n == 2) {
    printf("-1");
    return 0;
  }
  bool chk = 0;
  for (int i = 0; i < n; i++)
    if (a[i] != a[0]) {
      chk = 1;
      break;
    }
  if (!chk) {
    printf("-1");
    return 0;
  }
  for (int i = 0; i < n; i++) b[i] = a[i];
  sort(b, b + n);
  for (int i = 0; i < n; i++) d[i] = b[n - i - 1];
  for (int i = 0; i < n; i++)
    for (int j = i + 1; j <= n - 1; j++) {
      if (a[i] == a[j]) continue;
      swap(a[i], a[j]);
      if (unsort()) {
        printf("%d %d", i + 1, j + 1);
        return 0;
      }
      swap(a[i], a[j]);
    }
  printf("-1");
}
