#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>

using namespace std;

int main()
{
	ios::sync_with_stdio(false); cin.tie(0);

    int n; cin >> n;
	vector<int> sor(n);
	vector<int> indexek(n + 1);
	for (int i = 0; i < n; i++)
	{
		cin >> sor[i];
		indexek[sor[i]] = i + 1;
	}
	int maxd = 0, maxi = 0, maxj = 0;
	for (int i = 1; i < n+1; i++)
	{
		maxj = max(maxj, indexek[i - 1]);
		if (indexek[i] < maxj)
		{
			int prev = maxd;
			maxd = max(maxd, indexek[maxj] - indexek[i]);
			if (maxd != prev) maxi = indexek[i];
		}
	}
	if (maxd == 0) cout << -1;
	else cout << maxi << " " << maxj;
}