#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n;
    cin >> n;
    vector <int> v(n + 1);
    for (int i = 1; i <= n; i++)
    {
        cin >> v[i];
    }
    int i = 1, j, kez, veg;
    bool van = false;
    while (i < n && !van)
    {
        j = n;
        while (j > 0 && !van)
        {
            if (v[i] > v[j])
            {
                van = true;
                kez = i;
                veg = j;
            }
            j--;
        }
        i++;
    }
    if (van)
    {
        cout << kez << " " << veg;
    }
    else
    {
        cout << -1;
    }
    return 0;
}