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


int main()
{
	int n;
	cin >> n;
	vector<int> v(n);
	for(int i = 0; i < n; ++i)
	{
		cin >> v[i];
	}
	int max_profit = 0;
	int buy_day = -1, sale_day = -1;
	for(int i = 0; i < n; ++i)
	{
		for(int j = i + 1; j < n; ++j)
		{
			if(v[j]-v[i] > max_profit)
			{
				max_profit = v[j]-v[i];
				buy_day = i+1;
				sale_day = j+1;
			}
		}
	}
	if(buy_day == -1)
		cout << -1 << endl;
	else
		cout << buy_day << " " << sale_day << endl;
	return 0;
}