// Inverzio

#include <bits/stdc++.h>
using namespace std;

#define ls(N,T) for (int i = 0; i < N; i ++) cout << T[i] << ","

int main () {
	int N,M = 0,M_i,M_j;
	cin >> N;
	int T[N];
	for (int i = 0; i < N; i ++) {
		cin >> T[i];
	}
	for (int j = 0; j < N; j ++) {
		for (int i = 0; i < j-M; i ++) {
			if (T[i] > T[j]) {
				M = j-i;
				M_i = i+1;
				M_j = j+1;
			}
			if (M == N-1) break;
		}
		if (M == N-1) break;
	}
	if (M == 0) cout << "-1";
	else cout << M_i << " " << M_j << "\n";
}