#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n;
    cin >> n;
    vector<int> arr(n + 1, 0);
    for (int i=1; i <= n; i++) {
        cin >> arr[i];
    }
    int low = 1, high = n;
    while (low < high) {
        if (arr[low] > arr[high]) {
            cout << low << ' ' << high << '\n';
            return 0;
        }
        if (arr[low + 1] > arr[high]) {
            cout << low + 1 << ' ' << high << '\n';
            return 0;
        }
        if (arr[low] > arr[high - 1]) {
            cout << low << ' ' << high << '\n';
            return 0;
        }
        low++; high--;
    }
    cout << -1 << '\n';
    return 0;
}