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


int main() {
    int T;
    cin >>T;
    while(T--) {
        int n;
        cin >>n;
        int a[n][2];
        int min_x=INT_MAX,min_y=INT_MAX,max_x=INT_MIN,max_y=INT_MIN;
        for(int i=0;i<n;i++) {
            cin >>a[i][0]>>a[i][1];   
            min_x = min(a[i][0],min_x);
            max_x = max(a[i][0],max_x);
            min_y = min(a[i][1],min_y);
            max_y = max(a[i][1],max_y);
        }
        int flag = 1;
        for(int i=0;i<n && flag;i++) {
            if(a[i][0] == min_x && a[i][1]<=max_y){
                //cout << "left\n";
            }else if(a[i][0] == max_x && a[i][1]<=max_y){
                //cout << "right\n";
            }else if(a[i][1] == min_y && a[i][0]<=max_x){
                //cout << "bottum\n";
            }else if(a[i][1] == max_y && a[i][0]<=max_x){
                //cout << "top\n";
            }else {flag =0;}
        }
        if(flag) cout << "YES\n";
        else cout <<"NO\n";
    }
    return 0;
}