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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    long long int i,j,k,m,n,x[100],y[100],max=0,q;
    cin>>q;
    for(int d=0;d<q;d++)
        {
        cin>>n;
        for(i=0;i<n;i++)
        {cin>>x[i]>>y[i];
         if(x[i]>max)
            max=x[i];
         else if(y[i]>max)
             max=x[i];
             
        }
       
        for(i=0;i<n;i++)
            {
            if(x[i]!=0)
                {
                if(y[i]!=max&&y[i]!=0)
                    {
                    cout<<"NO"<<endl;
                    break;
                }
            }
            else if(y[i]!=0)
                {
                if(x[i]!=max&&x[i]!=0)
                    {
                    cout<<"NO"<<endl;
                    break;
                }
            }
        }
        if(i==n)
            cout<<"YES\n";
        
    }
    return 0;
}