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

int main() {
    int q;
    scanf("%d",&q);
    for(int q1=0;q1<q;q1++)
        {
        int n;
        scanf("%d",&n);
       int a[n],b[n],min1=10001,max1=-10001,min2=10001,max2=-10001;
        for(int i=0;i<n;i++){
            scanf("%d %d",&a[i],&b[i]);
           if(a[i]<min1)
               min1=a[i];
            if(a[i]>max1)
                max1=a[i];
            if(b[i]<min2)
               min2=b[i];
            if(b[i]>max2)
                max2=b[i];
        }int flag=0;
        for(int i=0;i<n;i++){
            if(a[i]==min1 || a[i]==max1){
               if(b[i]<=max2 && b[i]>=min2)
                   continue;
                else{
                    flag=1;break;
                }
            }else if(b[i]==min2 || b[i]==max2){
                if(a[i]<=max1 && a[i]>=min1)
                    continue;
                else{
                    flag=1;break;
                }
            }else{
                flag=1;
                break;
            }
    }
        if(flag==1)
            printf("NO\n");
        else
            printf("YES\n");
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    return 0;
}