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

int main() {
int t;
    scanf("%d",&t);
    while(t--)
        {
        int s,count=0;
        scanf("%d",&s);
        int c=s;
        while(s--)
            {
            int x,y,count1=0;
            scanf("%d%d",&x,&y);
            if((x==0)||(y==0))
                {
               count++;
            }
           
        }
      
        if(count==c)
            {
            printf("YES\n");
        }
        else
            {
            printf("NO\n");
        }
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    return 0;
}