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


int main() {
    int q, n, c;
    cin>>q;
    while(q--)
    {
        cin>>n;
        c=0;
        int x[n], y[n], a[n], b[n];
        for(int i=0; i<n; i++)
        {
            cin>>a[i]>>b[i];
            x[i]=a[i];
            y[i]=b[i];
        }
        sort(a, a+n);
        sort(b, b+n);
        for(int i=0; i<n; i++)
        {
            if(((x[i]==a[0]||x[i]==a[n-1])&&(y[i]>=b[0]&&y[i]<=b[n-1]))
               ||((y[i]==b[0]||y[i]==b[n-1])&&(x[i]>=a[0] &&x[i]<=a[n-1])))
                c++;
        }
        if(c==n)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
    return 0;
}