#include <bits/stdc++.h>
using namespace std;
int a[100010];
bool isok(int n) {
  int f1 = 0, f2 = 0;
  for (int i = 1; i < n; i++) {
    if (a[i - 1] < a[i]) f1 = 1;
    if (a[i - 1] > a[i]) f2 = 1;
    if (f1 && f2) return false;
  }
  return true;
}
int main() {
  set<int> S;
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    S.insert(a[i]);
  }
  if (S.size() == 1 || n == 2)
    cout << "-1" << endl;
  else {
    for (int i = 1; i < n; i++)
      if (a[i] != a[i - 1]) {
        swap(a[i], a[i - 1]);
        if (!isok(n)) {
          cout << i << " " << i + 1 << endl;
          return 0;
        }
        swap(a[i], a[i - 1]);
      }
    cout << "-1" << endl;
  }
}
