#include <list>
#include <iostream>
#include <vector>
#include <bitset>
#include <algorithm>

#define MOD ((long long) 1e9 + 7)

using namespace std;

int main() {
    int n;
    cin >> n;

    vector<int> s(n);

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

    for (int window = n - 1; window > 0; window--) {
        for (int l = 0; l + window < n; l++) {
            int r = l + window;
            if (s[l] > s[r])
            {
                cout << l + 1 << ' ' << r + 1;
                return 0;
            }
        }
    }

    cout << -1;

    return 0;
}