#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

	int n;
    int a[100001];

    cin >> n;

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

    int maxDiff = 0;
    int x, y;

    for (int i = 0; i < n - 1; i++) {
        for (int j = i + 1; j < n; j++) {
            if (a[i] > a[j]) {
                if (j - i > maxDiff) {
                    maxDiff = j - i;
                    x = i + 1;
                    y = j + 1;
                }
            }
        }
    }

    if (maxDiff) {
        cout << x << " " << y;
    }
    else {
        cout << "-1";
    }
}