#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int t;
  cin>>t;
  while(t!=0)
    {
    int n;
    cin>>n;
    int x[n],y[n],xinter,yinter;
    for(int i=0;i<n;++i)
    {
        cin>>x[i]>>y[i];
        if(x[i]==0 && y[i]!=0)
          {
            xinter=x[i];
        }
      if(y[i]==0 && x[i]!=0)
          {
            yinter=y[i];
      }
    }
    int breakpt=0;
    for(int i=0;i<n && breakpt!=1;++i)
     {
         
        if((x[i]>xinter || x[i]<xinter) &&(y[i]>yinter || y[i]<yinter) )
          breakpt=1;
    }
    if(breakpt)
    cout<<"NO"<<endl;
    else
      cout<<"YES"<<endl;
    t--;
  }
    return 0;
}