#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[100001] = {};
  int n;
  cin >> n;
  int isinc = 0;
  int isdec = 0;
  for (int i = 0; i < n; i++) cin >> a[i];
  isinc = 1;
  isdec = 1;
  if (n <= 2) {
    cout << -1 << endl;
    return 0;
  }
  for (int i = 0; i < n - 1; i++)
    if (a[i + 1] < a[i]) isinc = 0;
  for (int i = 0; i < n - 1; i++)
    if (a[i + 1] > a[i]) isdec = 0;
  if (isinc == 1 && isdec == 1) {
    cout << -1 << endl;
    return 0;
  }
  for (int i = 1; i < n; i++) {
    if (a[0] != a[i]) {
      swap(a[0], a[i]);
      isinc = 1;
      isdec = 1;
      for (int j = 0; j < n - 1; j++)
        if (a[j + 1] < a[j]) isinc = 0;
      for (int j = 0; j < n - 1; j++)
        if (a[j + 1] > a[j]) isdec = 0;
      if (isinc == 1 || isdec == 1) {
        swap(a[0], a[i]);
        continue;
      }
      cout << 1 << ' ' << i + 1 << endl;
      return 0;
    }
  }
  for (int i = 0; i < n; i++) {
    if (i != 1)
      if (a[1] != a[i]) {
        swap(a[1], a[i]);
        isinc = 1;
        isdec = 1;
        for (int j = 0; j < n - 1; j++)
          if (a[j + 1] < a[j]) isinc = 0;
        for (int j = 0; j < n - 1; j++)
          if (a[j + 1] > a[j]) isdec = 0;
        if (isinc == 1 || isdec == 1) {
          swap(a[1], a[i]);
          continue;
        }
        cout << 2 << ' ' << i + 1 << endl;
        return 0;
      }
  }
  cout << -1 << endl;
  return 0;
}
