#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 q;
    cin>>q;
        while(q--)
        {
        int n;
        cin>>n;
        
        pair<int,int> p[n];
        for(int i=0;i<n;i++)
            {
            cin>>p[i].first>>p[i].second;
        }
            
            sort(p,p+n);
            
        cout<<"YES"<<endl;    
    }
    return 0;
}