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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q;
    cin>>q;
    int i;
    for(i=0;i<q;i++)
    {
        int n;
        cin>>n;
        int x[n];
        int y[n];
        int j;
        for(j=0;j<n;j++)
        {
            cin>>x[j]>>y[j];
        }
        int max=-10001;
        int min=10001;
        for(j=0;j<n;j++)
        {
            if(x[j]<min)
                min=x[j];
            if(x[j]>max)
                max=x[j];
        }
        int d=0;
        for(j=0;j<n;j++)
        {
            if((x[j]<max&&x[j]>min)&&(y[j]<max&&y[j]>min))
            {
                d=1;
                cout<<"NO"<<endl;
                break;
            }
        }
        if(d==0)
            cout<<"YES"<<endl;
    }
            
    return 0;
}