#include <bits/stdc++.h>
using namespace std;
const int Max = 2e6 + 10;
const int Mod = 1e9 + 7;
const long long int Inf = 1LL << 62;
long long int mxval[Max];
long long int mxpos[Max];
long long int ar[Max];
bool Sorted(int n) {
  long long int asc = 0, dsc = 0;
  for (int i = 1; i < n; i++) {
    if (ar[i] > ar[i + 1]) {
      dsc++;
    }
    if (ar[i] < ar[i + 1]) {
      asc++;
    }
  }
  return !asc or !dsc;
}
int main() {
  long long int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> ar[i];
  }
  if (n <= 2) {
    cout << -1 << endl;
    return 0;
  }
  for (int i = 1; i < n; i++) {
    if (ar[i] != ar[i + 1]) {
      swap(ar[i], ar[i + 1]);
      if (Sorted(n)) {
        swap(ar[i], ar[i + 1]);
      } else {
        cout << i << " " << i + 1 << endl;
        return 0;
      }
    }
  }
  cout << -1 << endl;
  return 0;
}
