#include <iostream>
#include <cassert>
#include <vector>
#include <iomanip>

using namespace std;

const int N = (int) 1e5 + 7;

int x[N];
int y[N];
int n;

int main() {
  #ifdef LOCAL
  freopen("in", "r", stdin);
  #endif

  int q;
  scanf("%d", &q);
  while (q--) {
    scanf("%d", &n);
    int xmin = N, xmax = -N;
    int ymin = N, ymax = -N;
    for (int i = 1; i <= n; i++) {
      scanf("%d%d", &x[i], &y[i]);
      xmin = min(xmin, x[i]);
      ymin = min(ymin, y[i]);
      xmax = max(xmax, x[i]);
      ymax = max(ymax, y[i]);
    }
    if (xmin == xmax || ymin == ymax) {
      puts("YES");
    } else {
      bool bad = 0;
      for (int i = 1; i <= n; i++) {
        if (x[i] == xmin || x[i] == xmax) {
          if (!(ymin <= y[i] && y[i] <= ymax)) {
            bad = 1;
          }
        } else if (y[i] == ymin || y[i] == ymax) {
          if (!(xmin <= x[i] && x[i] <= xmax)) {
            bad = 1;
          }
        } else {
          bad = 1;
        }
      }
      puts(bad ? "NO" : "YES");
    }
  }
  return 0;
}