import java.io.*;
import java.util.*;

public class Solution {

    private static Scanner in = new Scanner(System.in);

    public static void main(String[] args) {
        int q = in.nextInt();
        for (int query = 0; query < q; query++) {
            solve(in.nextInt());
        }
        in.close();
    }
    
    private static void solve(int n) {
        int[][] vectors = new int[n][2];
        int maxX = 0, maxY = 0;
        int minX = 0, minY = 0;
        for (int i = 0; i < n; i++) {
            vectors[i][0] = in.nextInt();
            vectors[i][1] = in.nextInt();
            if (i == 0) {
                minX = vectors[i][0];
                maxX = vectors[i][0];
                minY = vectors[i][1];
                maxY = vectors[i][1];
            }
            if (vectors[i][0] > maxX) {
                maxX = vectors[i][0];
            } else if (vectors[i][0] < minX) {
                minX = vectors[i][0];
            }
            if (vectors[i][1] > maxY) {
                maxY = vectors[i][1];
            } else if (vectors[i][1] < minY) {
                minY = vectors[i][1];
            }
        }
        for (int i = 0; i < n; i++) {
            int x = vectors[i][0];
            int y = vectors[i][1];
            if ((x > minX && x < maxX) && (y > minY && y < maxY)) {
                System.out.println("NO");
                return;
            }
        }
        System.out.println("YES");
    }
}