#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n;
    cin>>n;
    vector<int> index(n+1);
    int tmp;
    for(int i=1;i<=n;i++)
        {
        cin>>tmp;
        index[tmp]=i;
        }
    int ii=-1,ji=-1;
    int max=0;
    for(int i=1;i<=n;i++)
        {
        if(index[i]>max)
            {
            max=index[i];
            }
        else
            {
            if(max-index[i]>ji-ii)
                {
                ji=max;
                ii=index[i];
                }
            }
        }
    if(ii==-1)
        {
        cout<<-1<<endl;
        }
    else
        {
        cout<<ii<<" "<<ji<<endl;
        }
    return 0;
}