#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 = n + 1, kez, veg;
    bool van = false;
    while (i < n && !van)
    {
        j--;
        if (v[i] > v[j])
        {
            kez = i;
            veg = j;
            van = true;
        }
        if (j = i + 1)
        {
            i++;
            j = n;
        }

    }
    if (van)
    {
        cout << kez << " " << veg;
    }
    else
    {
        cout << -1;
    }
    return 0;
}