#include <bits/stdc++.h>
using namespace std;
#define io ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ALL(x) x.begin(),x.end()
#define SZ(x) x.size()
#define PB push_back
#define MP make_pair
#define F first
#define S second
typedef long long LL;
typedef vector<int> VI;
typedef pair<int,int> PI;

bool compare(const pair<int,PI>&i ,const pair<int,PI>&j) {
   return i.F < j.F;
}

const int N=3e5+3;
int n,l,r;
pair<int,PI> a[N];

int main() {
   io;
   cin >> n;
   for(int i = 0; i < n; i++) {
      cin >> a[i].F >> a[i].S.F;
      a[i].S.S = i+1;
   }
   sort(a,a+n,compare);
   l = a[0].F;
   r = a[0].S.F;
   for(int i = 1; i < n; i++) {
      if(a[i].S.F <= r) {
         cout << a[i].S.S << " " << a[0].S.S;
         return 0;
      }
   }
   cout << "-1 -1";
}