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 in = new Scanner(System.in);

        int testCases = in.nextInt();

        for(int a0 = 0; a0 < testCases; a0++) {
        boolean right = true;
        	
        int iCorners = in.nextInt();
        
        for(int iC=0;iC<iCorners;iC++){
            BigDecimal iFirst = in.nextBigDecimal();
            BigDecimal iSecond = in.nextBigDecimal();
            
            if((iFirst.equals(new BigDecimal(0))) || (iSecond.equals(new BigDecimal(0))))
            {continue;}
            else{
            	right=false;
            	break;
            }
        	
        }
        
        	
		
		if(right){System.out.println("YES");}
		else{System.out.println("NO");}
        }
    }
}