#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n;
    cin >> n;
    vector <int> v(n+1);

    for (int i = 0; i < n; i++)
        {
            int x;
            cin >> x;
            v[x] = i+1;
        }

    int m = 0;
    int sz1;
    int k = 0;
    int sz2;

    for (int i = 1; i < n+1; i++)
        {
            if (v[i] > m)
            {
                m = v[i];
            }
            else
                {
                    if(m - v[i] > k)
                        {
                            k = m - v[i];
                            sz2 = v[i];
                            sz1 = m;
                        }
                }

        }
    if (k != 0)
        cout << sz2 << " " << sz1 << "\n";
    else
        cout << "-1\n";
    return 0;
}