#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n;
    vector <int> v;
    cin >> n;
    v.resize(n);
    for(int i = 0; i < n; i ++)
        cin >> v[i];
    bool t = 0;
    int k = n, i;
    while(k >= 2 && !t){
        i = 0;
        while(i <= n - k && !t){
            if(v[i] > v[k - i + 1]){
                t = 1;
                cout << i + 1 << " " << k - i + 1;
            }
            i ++;
        }
        k --;
    }
    if(!t)
        cout << "-1";
    return 0;
}