#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
long long t, n, x[90], i, j, k, l, r, y[90], a, b, c, d;
int main() {
    cin>>l;
    for(j=0;j<l;j++){
        cin>>n;
        a=c=-90000;
        b=d=90000;
        for(i=0;i<n;i++){
            cin>>x[i]>>y[i];
            a=max(a,x[i]);
            b=min(b,x[i]);
            c=max(c,y[i]);
            d=min(d,y[i]);
        }
        t=1;
        for(i=0;i<n;i++){
            if(x[i]!=a&&x[i]!=b&&y[i]!=c&&y[i]!=d){t=0;break;}
        }
        if(t)cout<<"YES\n";
        else cout<<"NO\n";
    }
    return 0;
}