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

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner in = new Scanner(System.in);
        int q = in.nextInt();
        
        for(int i= 0; i<q;i++)
        {
            int n = in.nextInt();
            int arr[][] = new int[n][2];
            
            
            int minx = 10000000;
            int miny = 10000000;
            int maxx = -10000000;
            int maxy = -10000000;
            
            for(int j= 0; j<n;j++)
            {
                arr[j][0] = in.nextInt();
                arr[j][1] = in.nextInt();

                if(arr[j][0]> maxx) maxx = arr[j][0];
                if(arr[j][1]> maxy) maxy = arr[j][1];
                if(arr[j][0]< minx) minx = arr[j][0];
                if(arr[j][1]< miny) miny = arr[j][1];
            }
            if(n <= 3)
            {
                System.out.println("YES");
                continue;
            }
//            if(minx == maxx || miny == maxy && n > 3) {
//                System.out.println("NO");
//                in.close();
//                return;
//            }
            boolean flag = true;
            for(int j= 0; j<n;j++)
            {
                if(arr[j][0]<= maxx && arr[j][0] >= minx && (arr[j][1]== maxy || arr[j][1] == miny)) {}
                else if (arr[j][1]<= maxy && arr[j][1] >= miny && (arr[j][0]== maxx || arr[j][0] == minx)) {}
                else
                {
                    flag = false;
                    break;
                }
            }
            if(flag)
            System.out.println("YES");
            else
                System.out.println("NO");
        }
        in.close();
    }
}