#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 */   
    int n;
    cin>>n;
    while(n--)
        {
        int n1,i=0,max=-1,n2,max1=-1;
        cin>>n1;n2=n1;
        int a[n1][2];
        while(n1--)
            {
            cin>>a[i][0]>>a[i++][1];
            if(max<a[i-1][1])
                max=a[i-1][1];
            if(max1<a[i-1][0])
                max1=a[i-1][0];
        }
        i=0;
        while(n2--)
            {
            if(a[i][1]==0 ||(a[i][0]==max1)||a[i][1]==max ||a[i][0]==0)
            i++;
            else
                break;
             }
if(n2<0)
    cout<<"YES\n";
        else
            cout<<"NO\n";
    }
    return 0;
}