#include <iostream>
using namespace std;

int a[500001]={0};

int main()
{
    int n,x;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>x;
        a[x]=i;
    }
    int maxt=0, indb, indj;
    x=1;
    for(int i=2;i<=n;i++)
    {
            if(a[i]<a[x])
            {
                int d=a[x]-a[i];
                if(d>maxt)
                {
                    maxt=d; indb=x; indj=i;
                }
            }
            else x=i;

    }
    if(maxt>0)
        cout<<a[indj]<<" "<<a[indb]<<endl;
    else
        cout<<-1;


    return 0;
}