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


int main() {
    int q,n,min=99999,max=0,flag=0;
    cin>>q;
    while(q--)
        {
        cin>>n;
        int arr[n],brr[n];
            for(int i=0;i<n;i++)
            {
            cin>>arr[i]>>brr[i];
               if(arr[i]<min)
                   min=arr[i];
                if((arr[i]>max)) max=arr[i];
        }
        for(int i=0;i<n;i++)
            {
            if(arr[i]>min && arr[i]<max)
                {
                if(brr[i]!=min || brr[i]!=max)
                {
                    flag=1;
                    break;
                }
            }
            else if(arr[i]<min || arr[i]>max)
                {
                flag=1;break;
            }
        }
        if(flag==1)
        cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
        flag=0;min=99999,max=0;
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}