#include <bits/stdc++.h>
using namespace std;
long long a[200006], b[200006], c[200006];
long long n;
bool check() {
  bool ok = 0, ok1 = 0;
  for (long long i = 0; i < n; i++) {
    if (a[i] != b[i]) {
      ok = 1;
      break;
    }
  }
  for (long long i = 0; i < n; i++) {
    if (a[i] != c[i]) {
      ok1 = 1;
      break;
    }
  }
  if (ok == 1 && ok1 == 1) return true;
  return false;
}
void solve() {
  cin >> n;
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
    b[i] = a[i];
    c[i] = a[i];
  }
  sort(b, b + n);
  sort(c, c + n, greater<long long>());
  for (long long i = 1; i < n; i++) {
    if (a[i] != a[i - 1]) {
      swap(a[i], a[i - 1]);
      bool ok = check();
      if (ok == true) {
        cout << i << " " << i + 1 << endl;
        return;
      }
      swap(a[i], a[i - 1]);
    }
  }
  cout << "-1" << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long t = 1;
  while (t--) solve();
  return 0;
}
