#include <bits/stdc++.h>
using namespace std;
unsigned long long min(unsigned long long x, unsigned long long y) {
  if (x < y) return x;
  return y;
}
unsigned long long max(unsigned long long x, unsigned long long y) {
  if (x < y) return y;
  return x;
}
long long min(long long x, long long y) {
  if (x < y) return x;
  return y;
}
long long max(long long x, long long y) {
  if (x < y) return y;
  return x;
}
double min(double x, double y) {
  if (x < y) return x;
  return y;
}
double max(double x, double y) {
  if (x < y) return y;
  return x;
}
unsigned long long gcd(unsigned long long x, unsigned long long y) {
  if (!x) return y;
  if (!y) return x;
  if (x > y) swap(x, y);
  return gcd(x, y % x);
}
unsigned long long inv(unsigned long long a, unsigned long long c) {
  if (a == 1) {
    return 1;
  }
  return ((c - (c / a)) * inv(c % a, c)) % c;
}
int n, l[300005] = {0}, r[300005] = {0}, idx[300005] = {0};
int comp(int a, int b) {
  if (l[a] == l[b]) return r[a] > r[b];
  return l[a] < l[b];
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> l[i] >> r[i];
    idx[i] = i;
  }
  sort(idx, idx + n, comp);
  int minr = r[idx[n - 1]], j = n - 1;
  for (int i = n - 2; i >= 0; --i) {
    if (minr <= r[idx[i]]) {
      cout << (idx[j] + 1) << " " << (idx[i] + 1) << "\n";
      return 0;
    }
    if (r[idx[i]] < minr) {
      j = i;
      minr = r[idx[i]];
    }
  }
  cout << "-1 -1\n";
  return 0;
}
