#include <iostream>

using namespace std;

int sor[500001];
int poz[500001];

int main()
{
    int N;
    cin >> N;
    for(int i = 1; i <= N; i++){
        cin >> sor[i];
        poz[sor[i]] = i;
    }
    int max_tav = 0;
    int index2 = N;
    int megoldas_bal, megoldas_jobb;
    for(int num = N; num >= 2; num--){
        int index1 = poz[num];
        while(sor[index2] >= num && index2 > 0){
            index2--;
        }
        if(index2 > 0 && index1 < index2 && index2 - index1 > max_tav){
            max_tav = index2 - index1;
            megoldas_bal = index1;
            megoldas_jobb = index2;
        }
    }
    if(max_tav != 0){
        cout << megoldas_bal << " " << megoldas_jobb << endl;
    }
    else{
        cout << -1 << endl;
    }
    return 0;
}