#include <bits/stdc++.h>
using namespace std;
#define ll long long

int main()
{
    int n; cin >> n;
    vector <int> S(n+1);
    for(int i = 1; i <= n; i++)
    {
        int s; cin >> s;
        S[s] = i;
    }
    int maxi = 0;
    int ansl = 0; int ansr = 0;
    int cur = 1;
    for(int i = 1; i <= n; i++)
    {
        if(S[i] > S[cur]) cur = i;
        else{
            if(S[cur] - S[i] > maxi)
            {
                ansl = S[cur];
                ansr = S[i];
                maxi = ansl - ansr;
            }
        }
    }
    if(maxi == 0){
        cout << -1;
        return 0;
    }
    cout << ansl << " " << ansr;
    return 0;
}