#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
#define mx 100000
#define mn -100000

int main() {
    int q;
    cin>>q;
    while(q--)
        {
        int n;
        cin>>n;
        int x1=mx,x2=mn,y1=mx,y2=mn;
        vector<int>x(n+1),y(n+1);
        for(int i=1;i<=n;i++)
            {
            cin>>x[i];
            cin>>y[i];
            if(x[i]<x1)
                   x1=x[i];
            if(x[i]>x2)
                x2=x[i];
            if(y[i]<y1)
                   y1=y[i];
            if(y[i]>y2)
                y2=y[i];
        }
        int fg=0;
        for(int i=1;i<=n;i++)
            {
            if((y[i]==y1 || y[i]==y2 ) && x[i]>=x1 && x[i]<=x2)
              continue;
            else if((x[i]==x1 || x[i]==x2) && y[i]>=y1 && y[i]<=y2)
                continue;
             else
                {
                fg=1;
                break;
            }
        }
        if(fg)
            cout<<"NO"<<endl;
        else
            cout<<"YES"<<endl;  
    }
    return 0;
}