#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>



int main(void) {
	
	int q;
	int x;
	int n, m;
	int  ans =0 ;
	scanf("%d", &q);
	
	
	while(q--)	{
		 
		scanf("%d", &x);
			
		
		while(x--)	{
			
			
			scanf ("%d %d", &n, &m);
			
			if (n ==0 || m ==0)	ans = 1;
			else ans = 0 ;
		}
		
		if (ans)	printf("YES");
		else printf("NO");
		
		printf("\n");
	}
	return 0;
}