#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
struct q{
    int x;
    int y;
};

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int n,q,xmin,xmax,ymin,ymax,i;
    cin>>q;
    while(q--){
        int flag=0;
        cin>>n;
        struct q a[n];
        for(i=0;i<n;++i)
            cin>>a[i].x>>a[i].y;
        xmin=a[0].x;
        xmax=a[0].x;
        ymin=a[0].y;
        ymax=a[0].y;
        for(i=1;i<n;++i){
            if(xmin>a[i].x)
                xmin=a[i].x;
            if(xmax<a[i].x)
                xmax=a[i].x;
            if(ymin>a[i].y)
                ymin=a[i].y;
            if(ymax<a[i].y)
                ymax=a[i].y;
        }
        for(i=0;i<n;++i){
            if(a[i].x==xmin || a[i].x==xmax || a[i].y==ymin || a[i].y==ymax)
                continue;
            else{
                flag=1;
                break;
            }
        }
        if(flag==0)
            cout<<"YES\n";
        else
            cout<<"NO\n";
    }
    return 0;
}