#include<bits/stdc++.h>
using namespace std;
int a[20],b[20];
int main() {
   int q;
   cin>>q;
   while(q--) {
     int n;
     cin>>n;
     int x,y;
     int min_x=INT_MAX,max_x=INT_MIN,min_y=INT_MAX,max_y=INT_MIN;
     int ind=0;
     int num=n;
     while(n--) {
        cin>>x>>y;
        a[ind]=x;
        b[ind]=y;
        ind++;
        if(x<min_x) min_x=x;
        if(x>max_x) max_x=x;
        if(y<min_y) min_y=y;
        if(y>max_y) max_y=y;
     }
     int i=0;int c=0,d=0,e=0,f=0;
     for(i=0;i<num;i++) {
      if(a[i]==min_x) c++;
    else   if(a[i]==max_x) d++;
     else  if(b[i]==min_y) e++;
      else if(b[i]==max_y) f++;
    
     }
     if(num==c+d+e+f)
        cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
   }
   return 0;
}