#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 t;
    cin>>t;
    while(t--) {
        int Mx = -10000;
        int My = -10000l;
        int mx = 10000;
        int my = 10000;
        int n;
        cin>>n;
        int x[n+1],y[n+1];
        for(int i=0;i<n;i++) {
            cin>>x[i]>>y[i];
            Mx = max(Mx, x[i]);
            My = max(My, y[i]);
            mx = min(mx, x[i]);
            my = min(my, y[i]);
        }
        int flag = 1;
        for(int i=0;i<n;i++) {
            if (x[i]>mx and x[i]<Mx) {
                if (y[i]!=my and y[i]!=My) {
                    flag=0;
                    break;
                }
            }
            if (y[i]>my and y[i]<My and (x[i]!=mx and x[i]!=Mx)) {
                flag=0;
                break;
            }
        }
        if(flag) cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
           
    }
    return 0;
}