#include <bits/stdc++.h>
using namespace std;
vector<int> adj[100001];
bool visit[100001];
const int mod = 1000000007;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n, i, arr[100001], inc[100001], dec[100001];
  cin >> n;
  for (long long i = 0; i < n; i += 1) {
    cin >> arr[i];
    inc[i] = arr[i];
    dec[i] = arr[i];
  }
  sort(inc, inc + n);
  sort(dec, dec + n, greater<int>());
  int f = 0;
  for (long long i = 0; i < n - 1; i += 1)
    if (arr[i] != arr[i + 1]) f = 1;
  if (n < 3 || !f)
    cout << -1;
  else {
    for (int k = 0; k < n; k++) {
      for (long long i = k + 1; i < n; i += 1) {
        int f = 0;
        if (arr[k] == arr[i]) continue;
        swap(arr[k], arr[i]);
        for (long long j = 0; j <= n - 1; j += 1) {
          if (arr[j] != inc[j]) {
            f = 1;
            break;
          }
        }
        if (f) {
          for (long long j = 0; j <= n - 1; j += 1) {
            if (arr[j] != dec[j]) {
              cout << k + 1 << " " << i + 1;
              return 0;
            }
          }
        }
        swap(arr[0], arr[i]);
      }
    }
    cout << -1;
  }
  return 0;
}
