#include <bits/stdc++.h>
using namespace std;
long long n, i, j, ans = 0, sz = 1e6 + 2;
bool cmp(pair<pair<long long, long long>, long long> &a,
         pair<pair<long long, long long>, long long> &b) {
  if (a.first.first == b.first.first) return a.first.second > b.first.second;
  return a.first.first < b.first.first;
}
vector<pair<pair<long long, long long>, long long> > v;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n;
  long long a, b;
  for (i = 1; i <= n; i++) cin >> a >> b, v.push_back({{a, b}, i});
  sort(v.begin(), v.end());
  for (i = 0; i < n; i++) {
    if (i != n - 1 and v[i].first.first <= v[i + 1].first.first and
        v[i].first.second >= v[i + 1].first.second) {
      cout << v[i + 1].second << " " << v[i].second;
      return 0;
    }
    if (i != 0 and v[i].first.first == v[i - 1].first.first and
        v[i].first.second >= v[i - 1].first.second) {
      cout << v[i - 1].second << " " << v[i].second;
      return 0;
    }
  }
  cout << -1 << " " << -1;
}
