#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 maxi = 0;
    bool van = false;
    int kez, veg;
    int x = 1;
    do
    {
        for (int i = n; i > x; i--)
        {
            if (v[x] > v[i])
            {
                if (i - x > maxi)
                {
                    maxi = i - x;
                    kez = x;
                    veg = i;
                    van = true;
                }
            }
        }
        x++;
    }
    while (!van);
    if (van)
    {
        cout << kez << " " << veg;
    }
    else
    {
        cout << -1;
    }
    return 0;
}