#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include<bits/stdc++.h>
using namespace std;


int main() {
    int t;cin>>t;
    while(t--){
        int n;cin>>n;
        vector<int> a(n);
        vector<int> b(n);
        for(int i=0;i<n;i++){
            cin>>a[i];
            cin>>b[i];            
        }
        int maxx=INT_MIN,maxy=INT_MIN;
        int minx=INT_MAX,miny=INT_MAX;
        for(int i=0;i<n;i++){
            if(a[i]>maxx) maxx=a[i];
            if(b[i]>maxy) maxy=b[i];
            if(a[i]<minx) minx=a[i];
            if(b[i]<miny) miny=b[i];
        }
        int f=0;
        for(int i=0;i<n;i++){
            if(a[i]==maxx || a[i]==minx || b[i]==maxy || b[i]==miny) continue;
            else{
                f=1;break;
            }
        }
        if(f) cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
    }
    return 0;
}