#include <bits/stdc++.h>
using namespace std;
const int maxn = 100005;
int a[maxn], b[maxn], c[maxn];
int n;
bool check() {
  int c1 = 0, c2 = 0;
  for (int i = 1; i <= n; i++) {
    if (a[i] != b[i]) c1 = 1;
  }
  for (int i = 1; i <= n; i++) {
    if (a[i] != c[i]) c2 = 1;
  }
  return (c1 & c2);
}
int fun() {
  for (int i = 1; i < n; i++) {
    if (a[i] != a[i + 1]) {
      swap(a[i], a[i + 1]);
      if (check()) {
        cout << i << " " << i + 1 << "\n";
        return 1;
      }
      swap(a[i], a[i + 1]);
    }
  }
  return -1;
}
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    b[i] = c[i] = a[i];
  }
  sort(b + 1, b + 1 + n);
  sort(c + 1, c + 1 + n, greater<int>());
  if (fun() == -1)
    cout << "-1"
         << "\n";
  return 0;
}
