#include <iostream>
#include <vector>
#include <array>
using namespace std;
#define speed cin.tie(0); ios::sync_with_stdio(0)

using point = array<int, 2>;

int main() {
    speed;

    int N;
    cin >> N;
    vector<int> v(N);
    for (int i = 0; i < N; i++) {
        cin >> v[i];
    }
    
    point p {0, 0};
    for (int i = 0; i < N; i++) {
        for (int j = i + 1 + (p[1] - p[0]); j < N; j++) {
            if (v[i] > v[j] && j - i > p[1] - p[0]) {
                p = {i, j};
            }
        }
    }

    if (p[0] || p[1]) {
        cout << p[0] + 1 << ' ' << p[1] + 1;
    } else {
        cout << -1;
    }
}