#include <cmath>
#include <cstdio>
#include <vector>
#include <bits/stdc++.h>
#include <algorithm>
using namespace std;
#define  m INT_MIN
#define Mx INT_MAX 
int main() {
    int q,n;
    cin>>q;
    while(q--){
        cin>>n;
        int x1,x2,y1,y2,lx=Mx,hx=m,ly=Mx,hy=m,x[n+1],y[n+1];
        bool f=1;
        for(int i=0;i<n;i++){
            cin>>x[i]>>y[i];
            
            if(x[i] < lx)lx=x[i];
            if(x[i] > hx)hx=x[i];
            if(y[i] < ly)ly=y[i];
            if(y[i] > hy)hy=y[i];
            
        }
        for(int i=0;i<n;i++){
            if(x[i]!=lx&&x[i]!=hx&&y[i]!=ly&&y[i]!=hy){
                f=0;break;
            }
        }
        if(f==1)cout<<"YES\n";
        else cout<<"NO\n";
    }
    return 0;
}