import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

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 sc=new Scanner(System.in);
        int q=sc.nextInt();
        boolean f=false;int t;int xt=0,yt=0;int []x;int []y;
        for(int i=0;i<q;i++){
            t=sc.nextInt();
            f=false;x=new int[t];y=new int[t];
            for(int j=0;j<t;j++){
                x[j]=sc.nextInt();
                y[j]=sc.nextInt();
                if(x[j]==0 && y[j]==0)
                    f=true;
                else if(x[j]!=0 && y[j]==0){
                    f=true;
                    xt=x[j];
                }
                else if(x[j]==0 && y[j]!=0){
                    f=true;
                    yt=y[j];
                }else if(x[j]==xt && y[j]<=yt && y[j]>=0 && xt>0)
                    f=true;
                    else if(y[j]==yt && x[j]<=xt && x[j]>=0 && yt>0)
                    f=true;
                    else if(x[j]==xt && y[j]>=yt && y[j]<=0 && xt<0)
                    f=true;
                    else if(y[j]==yt && x[j]>=xt && x[j]<=0 && yt<0)
                    f=true;
                    else{
                    f=false;break;
                    }
            }
            if(f)
                System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
}