#include<bits/stdc++.h>
using namespace std;
int main()
{
  vector <pair<int,int> > v;
  int i,n,q,x,y,min1=100000,max1=-100000,min2=100000,max2=-100000;
  scanf("%d",&q);
  while(q--)
  {
    scanf("%d",&n);
   while(n--)
   {
    scanf("%d %d",&x,&y);
    if(x<min1)
        min1=x;
    if(x>max1)
        max1=x;
    if(y<min2)
        min2=y;
    if(y>max2)
        max2=y;
    v.push_back(make_pair(x,y));
   }
   sort(v.begin(),v.end());
   for(i=0;i<v.size();++i)
   {
     if(((v[i].first==min1) || (v[i].first==max1)) && ((v[i].second>=min2) && (v[i].second<=max2)))
      continue;
     else if(((v[i].second==min2) || (v[i].second==max2)) && ((v[i].first>=min1) && (v[i].first<=max1)))
      continue;
     else
        break;
   }
   if(i==v.size())
    printf("YES\n");
   else
    printf("NO\n");
  }
  return 0;
}