#include <bits/stdc++.h>
using namespace std;
int n, a[100005];
int test(int x, int y) {
  swap(a[x], a[y]);
  int da = 0, xi = 0;
  for (int i = 2; i <= n; i++) {
    if (a[i] > a[i - 1])
      da = 1;
    else if (a[i] < a[i - 1])
      xi = 1;
  }
  swap(a[x], a[y]);
  return da + xi;
}
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  if (n <= 2)
    cout << -1 << endl;
  else {
    int p = 0;
    for (int i = 2; i < n; i++)
      if (a[i] != a[1] || a[i] != a[n]) {
        p = i;
        break;
      }
    if (p) {
      int i;
      for (i = 1; i <= n; i++) {
        if (a[p] != a[i] && test(i, p) == 2) {
          cout << i << " " << p << endl;
          break;
        }
      }
      if (i > n) cout << -1 << endl;
    } else
      cout << -1 << endl;
  }
}
