#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;
    while(q--)
    {
        int n;
        cin>>n;
        int x[n],y[n];
        int i,j;
        for(i=0;i<n;i++)
        {
            cin>>x[i];
            cin>>y[i];
        }
        int sx=0,lx=0,sy=0,ly=0;
        for(i=0;i<n;i++)
        {
            if(x[i]<sx)
                sx=x[i];
            if(y[i]<sy)
                sy=y[i];
            if(x[i]>sx)
                lx=x[i];
            if(y[i]>ly)
                ly=y[i];

        }
        int flag=0;
        for(i=0;i<n;i++)
        {
            if(((x[i]>=sx) && (x[i]<=lx) && (y[i]==sy || y[i]==ly)) || ((y[i]>=sy) && (y[i]<=ly) && (x[i]==sx || x[i]==lx)) )
                flag++;
        }
        if(flag==n)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
    return 0;
}