#include <bits/stdc++.h>

using namespace std;

int main()
{
    int n;
    cin >> n;
    vector<int> sor (n);
    vector<int> szsor (n);
    for (int i = 0; i < n; i++) {
        cin >> sor[i];
        szsor[sor[i] - 1] = i;
    }
    int maxind = 0;
    int ind_1 = 0;
    int ind_2 = 0;
    int tav = 0;
    for (int i = 1; i < n; i++) {
        maxind = max(maxind, szsor[i - 1]);
        //cout << maxind << " " << szsor[i] << "\n";
        if (maxind - szsor[i] > tav) {
            ind_1 = szsor[i];
            ind_2 = maxind;
            tav = maxind - szsor[i];
            //cout << tav << " " << ind_1 << " " << ind_2 << "\n";
        }
    }
    if (tav > 0) {
        cout << ind_1 + 1 << " " << ind_2 + 1;
    } else {
        cout << "-1";
    }
}