#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,n,i,j;
    cin>>q;
    for(i=0;i<q;i++){
        cin>>n;
        long int x[n],y[n];
        int maxX,minX,maxY,minY;
        for(j=0;j<n;j++){
            cin>>x[j]>>y[j];
            if(j==0){
                maxX=x[j];
                minX=x[j];
                maxY=y[j];
                minY=y[j];
            }
            else{
                if(maxX<x[j])
                    maxX=x[j];
                if(minX>x[j])
                    minX=x[j];
                if(maxY<y[j])
                    maxY=y[j];
                if(minY>y[j])
                    minY=y[j];
            }
        }
        int flag = 0;
        for(j=0;j<n;j++){
            if(((x[j]==minX || x[j]==maxX) && (y[j]>=minY || y[j]<=maxY)) || ((y[j]==minY || y[j]==maxY) && (x[j]>=minX || x[j]<=maxX))){
             continue;   
            }
            else
                flag = 1;
                break;
        }
        if(flag==1)
            cout<<"NO\n";
        else
            cout<<"YES\n";
    }
    
    return 0;
}