#include<iostream>
#include<vector>

using namespace std;

int main()
{
    int n;
    cin >> n;
    vector<int> v(n);

    for(int i = 0; i < n; i++)
    {
        cin >> v[i];
    }

    int b = -1, e = -1;
    for(int i = 0; i < n; i++)
    {
        for(int j = n - 1; j >= 0; j--)
        {
            if(v[i] > v[j])
            {
                b = i + 1;
                e = j + 1;
                break;
            }
        }
        if(e != -1)
        {
            break;
        }
    }
    if(e != -1)
    {
        cout << b << " " << e;
    }
    else
    {
        cout << -1;
    }
}