#include <bits/stdc++.h>
int t, i, j, a, b, n, bestIndex = -1, bestPoint = -1;
using namespace std;
int main() {
  cin >> t;
  for (i = 1; i <= t; i++) {
    cin >> n;
    for (j = 1; j <= n; j++) {
      cin >> a >> b;
      if (a <= 10 && b > bestPoint) {
        bestPoint = b;
        bestIndex = j;
      }
    }
    cout << bestIndex << endl;
  }
  return 0;
}