#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int n, t, p1, p2, maxi, tav = -1;

vector<pair<int, int>> v;

int main()
{
	cin >> n;
	for (int i=1;i<=n;++i)
	{
		cin >> t;
		v.push_back({ t,i });
	}
	sort(v.begin(), v.end());
	for (auto& i : v)
	{
		if (i.second > maxi)
			maxi = i.second;
		else if (maxi - i.second > tav)
		{
			tav = maxi - i.second;
			p1 = i.second;
			p2 = maxi;
		}
	}
	if (tav == -1)
		cout << tav;
	else cout << p1 << " " << p2;
}