#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

struct adat
{
    int nr, original_index, curr_max_index;
};

int comp(adat a, adat b)
{
    return a.nr < b.nr;
}

vector<adat> x;
pair<int, int> sol;
int n, i, maximum_dist, maximum_index;

int main()
{
    cin >> n;
    x.resize(n + 1);

    for (i = 1; i <= n; ++i)
    {
        cin >> x[i].nr;
        x[i].original_index = i;
    }

    sort(x.begin(), x.end(), comp);

    for (i = 1; i <= n; ++i)
    {
        if (x[i].original_index > maximum_index)
        {
            maximum_index = x[i].original_index;
        }
        x[i].curr_max_index = maximum_index;
    }

    /* for (auto &e : x)
    {
        cout << e.nr << " ";
    }
    cout << endl;
    for (auto &e : x)
    {
        cout << e.original_index << " ";
    }
    cout << endl;
    for (auto &e : x)
    {
        cout << e.curr_max_index << " ";
    } */

    maximum_dist = 0;
    for (i = 1; i <= n; ++i)
    {
        if (x[i].original_index < x[i].curr_max_index && x[i].curr_max_index - x[i].original_index > maximum_dist)
        {
            maximum_dist = x[i].curr_max_index - x[i].original_index;
            sol.first = x[i].original_index;
            sol.second = x[i].curr_max_index;
        }
    }

    if (maximum_dist == 0)
        cout << -1;
    else
        cout << sol.first << " " << sol.second;

    return 0;
}