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

public class Solution 
{
    public static void main(String[] args) 
    {
        Scanner sc = new Scanner(System.in);
        int q = sc.nextInt();
        while(q-->0)
        {
            int n = sc.nextInt();
            int a[][] = new int[n][2];
            for(int i=0;i<n;i++)
            {
                a[i][0]=sc.nextInt();
                a[i][1]=sc.nextInt();
            }
            if(n==1 || n==2)
                System.out.println("YES");
            else if(n==3)
            {
                double d1 = ((a[1][0]-a[2][0])*(a[1][0]-a[2][0])) + ((a[1][1]-a[2][1])*(a[1][1]-a[2][1]));
                double d2 = ((a[0][0]-a[2][0])*(a[0][0]-a[2][0])) + ((a[0][1]-a[2][1])*(a[0][1]-a[2][1]));
                double d3 = ((a[1][0]-a[0][0])*(a[1][0]-a[0][0])) + ((a[1][1]-a[0][1])*(a[1][1]-a[0][1]));
                
                if(d1==(d2+d3) || d2==(d1+d3) || d3==(d1+d2))
                    System.out.println("YES");
                else
                    System.out.println("NO");
            }
            else
            {
                int codx[] = new int[2];
                int cody[] = new int[2];
                int x=0,y=0;
                int px,py;
                int c1,c2;
                for(int i=0;i<n;i++)
                {
                    c1=0;c2=0;
                    px=a[0][0];
                    py=a[0][1];
                    for(int j=0;j<n;j++)
                    {
                        if(a[j][0]==px)
                            c1++;
                        if(a[j][1]==py)
                            c2++;
                    }
                    if(c1>=2 && x<2)
                        codx[x++]=px;
                    if(c2>=2 && y<2)
                        cody[y++]=py;
                }
                int flag=1;
                
                for(int i=0;i<n;i++)
                {
                    if(a[i][0]==codx[0] || a[i][0]==codx[1] || a[i][1]==cody[0] || a[i][1]==cody[1])
                        continue;
                    else
                        flag=0;
                }
                if(flag==1)
                    System.out.println("YES");
                else
                    System.out.println("NO");
            }
            
            
        }
    }
}