#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

int main()
{
long long n;
cin >> n;
bool a = true;
vector<long long> V(n, 0);
vector<long long> S(n + 1, 0);
for(long long i = 0; i < n; i++) {
cin >> V[i];
S[V[i]] = i + 1;
}
long long m = S[1];
long long megold = 0;
pair<long long,long long> s;
for(long long i = 2; i <= n; i++) {
if(S[i] > m) {
m = S[i];
}
if(S[i] < m) {
if(m - S[i] > megold) {
megold = m - S[i];
s.first = S[i];
s.second = m;
}
}
}
if(megold == 0) {
cout << "-1";
}else{
cout << s.first << " " << s.second;
}
}