#include <iostream>
#include <bits/stdc++.h>

using namespace std;

int main()
{
     int n, a, maxs=0, mins, h=0, y=0;
     cin>>n;
     vector<int> tav(n+1);
     tav[0]=-1;
     for(int i=1; i<=n; i++){
        cin>>a;
        tav[a]=i;
     }
     for(int i=1; i<=n; i++){
        if(tav[i]>y){
            y=tav[i];
        }
        else if(y-tav[i]>h){
            h=y-tav[i];
            mins=tav[i];
            maxs=y;
        }
     }
     if(h==0){
        cout<<-1;
     }
     else
     cout<<mins<<" "<<maxs;

}