#include <bits/stdc++.h>
using namespace std;
vector<long long> vec, a, b;
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    vec.push_back(x);
    a.push_back(x);
    b.push_back(x);
  }
  sort(a.begin(), a.end());
  sort(b.rbegin(), b.rend());
  for (int i = 1; i < n; i++) {
    if (vec[i] != vec[i - 1]) {
      swap(vec[i], vec[i - 1]);
      {
        if (vec != a && vec != b) {
          cout << i << " " << i + 1 << endl;
          return 0;
        }
      }
      swap(vec[i], vec[i - 1]);
    }
  }
  cout << "-1" << endl;
  return 0;
}
