#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 20;
int n, i, x;
vector<int> a, b, c;
int main() {
  scanf("%d", &n);
  for (i = 0; i < n; i++) scanf("%d", &x), a.push_back(x);
  c = b = a;
  sort(b.begin(), b.end());
  sort(c.rbegin(), c.rend());
  for (i = 1; i < n; i++) {
    if (a[i] != a[i - 1]) {
      swap(a[i], a[i - 1]);
      if (a != b && c != a) {
        printf("%d %d", i, i + 1);
        return 0;
      }
      swap(a[i], a[i - 1]);
    }
  }
  printf("-1");
  return 0;
}
