#include <bits/stdc++.h>
using namespace std;
bool cmp(pair<int, pair<long long, long long>> p1,
         pair<int, pair<long long, long long>> p2) {
  if (p1.second.first < p2.second.first)
    return true;
  else if (p1.second.first == p2.second.first)
    return p1.second.second > p2.second.second;
  return false;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  vector<pair<int, pair<long long, long long>>> v;
  for (int i = 0; i < n; i++) {
    long long x, y;
    cin >> x >> y;
    v.push_back({i + 1, make_pair(x, y)});
  }
  sort(v.begin(), v.end(), cmp);
  long long mx = 0;
  int ind = -1;
  int in = -1;
  for (int i = 0; i < n; i++) {
    if (v[i].second.second <= mx) {
      in = v[i].first;
      break;
    } else {
      mx = v[i].second.second;
      ind = v[i].first;
    }
  }
  if (in == -1)
    cout << -1 << " " << -1 << endl;
  else
    cout << in << " " << ind << endl;
  return 0;
}
