#include <bits/stdc++.h>
using namespace std;
map<int, int> p;
int main() {
  int i, j, m, n;
  int s[100100];
  while (cin >> n) {
    int mark = 0;
    int k = 0;
    for (i = 1; i <= n; i++) scanf("%d", &s[i]);
    for (j = 1; j < n; j++) {
      if (s[j] != s[j + 1]) {
        int r = 0;
        swap(s[j], s[j + 1]);
        for (i = 1; i < n; i++) {
          if (s[i] < s[i + 1]) {
            r++;
            break;
          }
        }
        for (i = 1; i < n; i++) {
          if (s[i] > s[i + 1]) {
            r++;
            break;
          }
        }
        swap(s[j], s[j + 1]);
        if (r < 2)
          continue;
        else {
          cout << j << ' ' << j + 1 << endl;
          mark = 1;
          break;
        }
      }
    }
    if (mark == 0) cout << "-1" << endl;
  }
  return 0;
}
