#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int t,n=0,i=0,j,c=0,m1,m2,m3,m4,f=0;
    cin>>t;
    while(t--){
        cin>>n;
        int a[n][2];f=0;
        for(i=0;i<n;i++){
            cin>>a[i][0]>>a[i][1];
            if(i==0){
                m1=a[i][0];
                m2=a[i][1];
                m3=a[i][0];
                m4=a[i][1];
            }
            if(m1<a[i][0])
                m1=a[i][0];
            if(m2<a[i][1])
                m2=a[i][1];
            if(m3>a[i][0])
                m3=a[i][0];
            if(m4>a[i][1])
                m4=a[i][1];
            
        }
        for(i=0;i<n;i++){
            if(m1==a[i][0]||m2==a[i][1]||m3==a[i][0]||m4==a[i][1]||m1==a[i][1]||m2==a[i][0]||m3==a[i][1]||m4==a[i][0])
                f=0;
            else{f=1;break;}
        }
        if(f==1)
            cout<<"NO\n";
        else
            cout<<"YES\n";
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}