#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);
    bool in_order = true;
    for (int i = 0; i < N; i++) {
        cin >> v[i];
        if (v[i] < v[i - 1]) in_order = false;
    }
    if (in_order) {
        cout << -1;
        exit(0);
    }
    point p {0, 0};
    for (int l = N; l > 0; l--) {
        for (int i = 0, j = l - 1; j < N; i++, j++) {
            if (v[i] > v[j]) {
                cout << i + 1 << ' ' << j + 1;
                exit(0);
            }
        }
    }
}