#include <bits/stdc++.h>
using namespace std;
const long double pi = 2 * acos(0.0);
template <class T>
bool umin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool umax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T lcm(T a, T b) {
  return a * (b / gcd(a, b));
}
template <class T, class TT>
bool pal(T a, TT n) {
  int k = 0;
  for (int i = 0; i <= n / 2; i++) {
    if (a[i] != a[n - i - 1]) {
      k = 1;
      break;
    }
  }
  return k ? 0 : 1;
}
bool mm(pair<pair<long long, long long>, int> x,
        pair<pair<long long, long long>, int> y) {
  if (x.first.first == y.first.first) return x.first.second > y.first.second;
  return x.first.first < y.first.first;
}
int main() {
  int n;
  cin >> n;
  int id = 0;
  vector<pair<pair<long long, long long>, int>> a;
  for (int i = 1; i <= n; i++) {
    long long l, r;
    cin >> l >> r;
    a.push_back({{l, r}, i});
  }
  sort(a.begin(), a.end(), mm);
  long long curl = 0, curr = -1;
  for (int i = 0; i < a.size(); i++) {
    long long l = a[i].first.first, r = a[i].first.second;
    int curid = a[i].second;
    if (l >= curl && r <= curr) {
      cout << curid << ' ' << id;
      return 0;
    }
    if (r >= curr) {
      curr = r;
      curl = l;
      id = curid;
    }
  }
  cout << -1 << ' ' << -1;
  getchar();
  getchar();
  return 0;
}
