#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100 * 1000 + 10;
int n;
int xs[MAXN];
bool all_equal() {
  for (int i = 1; i < n; ++i)
    if (xs[i] != xs[0]) return false;
  return true;
}
bool sorted() {
  bool inc = true;
  for (int i = 0; inc && i < n - 1; ++i) inc = xs[i] <= xs[i + 1];
  bool dec = true;
  for (int i = 0; !inc && dec && i < n - 1; ++i) dec = xs[i] >= xs[i + 1];
  return inc || dec;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> xs[i];
  if (n > 2 && !all_equal()) {
    int k = 0;
    for (int i = 0; k < 3 && i < n - 1; ++i)
      for (int j = i + 1; k < 3 && j < n; ++j)
        if (xs[i] != xs[j]) {
          swap(xs[i], xs[j]);
          if (!sorted()) {
            cout << i + 1 << ' ' << j + 1 << endl;
            return 0;
          }
          swap(xs[i], xs[j]);
          ++k;
        }
  }
  cout << -1 << endl;
  return 0;
}
