#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j;
  cin >> n;
  vector<int> a(n);
  set<int> s;
  for (i = 0; i < n; i = i + 1) {
    cin >> a[i];
    s.insert(a[i]);
  }
  if (n == 1 || n == 2 || s.size() == 1) {
    cout << "-1" << endl;
  } else {
    int r = 0, k, c, d;
    for (i = 0; i < n - 1; i = i + 1) {
      for (j = i + 1; j < n; j = j + 1) {
        if (a[i] != a[j]) {
          vector<int> b(n);
          b = a;
          swap(b[i], b[j]);
          c = 0, d = 0;
          for (k = 0; k < n - 1; k = k + 1) {
            if (b[k] > b[k + 1])
              c = c + 1;
            else if (b[k] < b[k + 1])
              d = d + 1;
            if (c > 0 && d > 0) break;
          }
          if (c > 0 && d > 0) {
            cout << i + 1 << " " << j + 1 << endl;
            break;
          }
        }
      }
      if (c > 0 && d > 0) break;
    }
    if (c == 0 || d == 0) cout << "-1" << endl;
  }
}
