#include <bits/stdc++.h>
using namespace std;
const int MAXN = 300010;
pair<pair<int, int>, pair<int, int> > allNums[MAXN * 2];
set<pair<int, int> > startTimes;
pair<int, int> v[MAXN];
int main() {
  int N;
  scanf("%d", &N);
  for (int i = 0; i < N; ++i) {
    scanf("%d%d", &v[i].first, &v[i].second);
    int L = v[i].second - v[i].first;
    allNums[2 * i] = make_pair(make_pair(v[i].first, 0), make_pair(L, i));
    allNums[2 * i + 1] = make_pair(make_pair(v[i].second, 1), make_pair(L, i));
  }
  sort(allNums, allNums + 2 * N);
  for (int i = 0; i < 2 * N; ++i) {
    if (allNums[i].first.second == 0) {
      startTimes.insert(
          make_pair(allNums[i].first.first, allNums[i].second.second));
      continue;
    }
    int idx = allNums[i].second.second;
    int st = v[idx].first;
    set<pair<int, int> >::iterator it = startTimes.find(make_pair(st, idx));
    set<pair<int, int> >::iterator snd = startTimes.begin();
    if (it == snd) ++snd;
    if (snd != startTimes.end() && snd->first <= it->first) {
      printf("%d %d\n", idx + 1, snd->second + 1);
      return 0;
    }
    startTimes.erase(it);
  }
  puts("-1 -1");
  return 0;
}
