#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> v(n), a, b;
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  a = v;
  b = v;
  sort(a.begin(), a.end());
  sort(b.begin(), b.end(), greater<int>());
  for (int i = 0; i < n - 1; i++) {
    if (v[i] != v[i + 1]) {
      swap(v[i], v[i + 1]);
      if (a == v || b == v) {
        swap(v[i], v[i + 1]);
        continue;
      }
      cout << i + 1 << " " << i + 2;
      return 0;
    }
  }
  cout << -1;
  return 0;
}
