import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        PointsOnRectangle solver = new PointsOnRectangle();
        solver.solve(1, in, out);
        out.close();
    }

    static class PointsOnRectangle {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int q = in.nextInt();
            for (int i = 0; i < q; i++) {
                int n = in.nextInt();
                int points[][] = new int[n][2];
                for (int j = 0; j < n; j++) {
                    for (int k = 0; k < 2; k++) {
                        points[j][k] = in.nextInt();
                    }
                }


                if (isCorrect(points)) {
                    out.println("YES");
                } else {
                    out.println("NO");
                }
            }
        }

        public boolean isCorrect(int[][] points) {
            int max = Integer.MIN_VALUE;
            int min = Integer.MAX_VALUE;
            int len = points.length;
            int min_x = 0;
            int min_y = 0;
            int max_x = 0;
            int max_y = 0;

            int d_min = min;
            for (int i = 0; i < len; i++) {
                if (points[i][0] < d_min) {
                    d_min = points[i][0];
                }
            }
            min_x = d_min;
            d_min = min;
            for (int i = 0; i < len; i++) {
                if (points[i][1] < d_min) {
                    d_min = points[i][1];
                }
            }
            min_y = d_min;
            d_min = min;

            int d_max = max;
            for (int i = 0; i < len; i++) {
                if (points[i][0] > d_max) {
                    d_max = points[i][0];
                }
            }
            max_x = d_max;
            d_max = max;

            for (int i = 0; i < len; i++) {
                if (points[i][1] > d_max) {
                    d_max = points[i][1];
                }
            }
            max_y = d_max;
            d_max = max;


            for (int i = 0; i < len; i++) {

                int x = points[i][0];
                int y = points[i][1];

                if (x == min_x || x == max_x) {
                    if (!(y >= min_y && y <= max_y)) {
                        return false;
                    }
                } else if (x > min_x && x < max_x) {
                    if (!(y == min_y || y == max_y)) {
                        return false;
                    }
                }


            }

            return true;


        }

    }
}