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

public class Solution {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int q = scanner.nextInt();
        for (int it = 0; it < q; it++) {
            int i = scanner.nextInt();
            if (i <= 3) {
                System.out.println("YES");
                for (int j = 0; j < i; j++) {
                    scanner.nextInt();
                    scanner.nextInt();
                }
                continue;
            }
            List<Integer[]> points = new ArrayList<>();
            int minx = 0;
            int miny = 0;
            int maxx = 0;
            int maxy = 0;
            if (i > 0) {
                int x = scanner.nextInt();
                int y = scanner.nextInt();
                points.add(new Integer[] {x, y});
                minx = x;
                maxx = x;
                miny = y;
                maxy = y;
            }
            for (int j = 1; j < i; j++) {
                int x = scanner.nextInt();
                int y = scanner.nextInt();
                points.add(new Integer[] {x, y});
                if (x < minx) {
                    minx = x;
                } else if (x > maxx) {
                    maxx = x;
                }
                
                if (y < miny) {
                    miny = y;
                } else if (y > maxy) {
                    maxy = y;
                }
            }
            boolean result = true;
            for (Integer[] ints : points) {
                if ((ints[0] != minx && ints[0] != maxx) || (ints[1] != miny && ints[1] != maxy)) {
                    result = false;
                }
            }
            System.out.println(result ? "YES" : "NO");
        }
    }
}