#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
    int n; cin >> n;
    vector<pair<int, int>> v(n + 1);
    for (int i = 1; i <= n; ++i) {
        v[i].second = i;
        cin >> v[i].first;
    }

    sort(v.begin(), v.end());
    int maxi = 0, res = -1, kezd = -1, ind = -1;
    for (auto& e : v) {
        if (maxi > e.second) maxi = e.second;
        else if (maxi - e.second > res) {
            res = maxi - e.second;
            kezd = e.second;
            ind = maxi;
        }
    }
    if (res == -1) cout << res;
    else cout << kezd << " " << ind << "\n";
}