#include <iostream>
#include <vector>
using namespace std;

int main() {
	int n;
	cin >> n;
	vector<int> best(n, -1);
	int bb = 0, be = 0;
	for (int i = 0; i < n; i++) {
		int x;
		cin >> x;
		if (best[x - 1] != -1) {
			if (i - best[x - 1] > be - bb) {
				bb = best[x - 1]; be = i;
			}
		}
		else {
			for (int j = x - 2; j >= 0; j--) {
				if (best[j] == -1) best[j] = i;
				else break;
			}
		}
	}
	if (bb == be) {
		cout << -1;
		return 0;
	}
	cout << bb + 1 << " " << be + 1;
	return 0;
}