/*
 * BWIDOW.cpp
 *
 *  Created on: Jun 3, 2014
 *      Author: Arpit Bhayani
 */

#include <cstdio>
#include <cstdlib>
#include <iostream>

using namespace std;

#define DEBUG 0
#define gc getchar
#define ll long long

void scanint(ll int &x) {
    register ll int c = gc();
    x = 0;
    for (; (c < 48 || c > 57); c = gc())
        ;
    for (; c > 47 && c < 58; c = gc()) {
        x = (x << 1) + (x << 3) + c - 48;
    }
}

int main(int argc, char * argv[]) {

    int t;
    scanf("%d", &t);
    while (t--) {
        ll int n, maxi = 0, maxo = 0, index = 0;
        scanint(n);
        for (ll int i = 0; i < n; i++) {
            ll int x, y;
            scanint(x);
            scanint(y);
            if (x > maxi) {
                maxi = x;
                index = i + 1;
            } else if (y > maxo) {
                maxo = y;
            }
        }
        if (maxi > maxo) {
            cout << index << endl;
        } else {
            cout << -1 << endl;
        }
    }
    return 0;
}