#include <bits/stdc++.h>
using namespace std;
int n, Max;
int num[100005];
map<int, int> m;
int main() {
  int in;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> num[i];
    m[num[i]]++;
    if (Max < m[num[i]]) {
      Max = m[num[i]];
      in = num[i];
    }
  }
  if (n <= 2) {
    cout << -1 << endl;
    return 0;
  }
  if (Max == n) {
    cout << -1 << endl;
    return 0;
  }
  if (Max == 1) {
    if (num[0] > num[1]) {
      for (int i = 1; i < n - 1; i++)
        if (num[i] > num[i + 1]) {
          printf("%d %d\n", i + 1, i + 2);
          return 0;
        }
      cout << 1 << " " << n << endl;
    }
    if (num[0] < num[1]) {
      for (int i = 1; i < n - 1; i++)
        if (num[i] < num[i + 1]) {
          printf("%d %d\n", i + 1, i + 2);
          return 0;
        }
      cout << 1 << " " << n << endl;
    }
    return 0;
  } else {
    int tmp, pos1 = -1, pos2 = -1;
    for (int i = 0; i < n; i++)
      if (num[i] == in) pos2 = i;
    for (int i = 0; i < n; i++)
      if (num[i] == in) {
        pos1 = i;
        break;
      }
    if (pos1 != 0) {
      cout << 1 << " " << pos1 + 1 << endl;
      return 0;
    }
    if (pos2 != n - 1) {
      cout << pos2 + 1 << " " << n << endl;
      return 0;
    }
    if (n == 3 && pos1 == 0 && pos2 == n - 1) {
      cout << -1 << endl;
      return 0;
    }
    for (int i = 1; i < n - 1; i++)
      if (num[i] != num[i + 1]) {
        cout << i + 1 << " " << i + 2 << endl;
        return 0;
      }
    for (int i = 1; i < n - 1; i++)
      if (num[i] != num[0]) {
        cout << 1 << " " << i + 1 << endl;
        return 0;
      }
  }
  return 0;
}
