#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;
    int n;
    int x1, x2, y1, y2;
    int flag=0;
    cin>>q;
    while (q--){
        cin>>n;
        vector<int> x (n);
        vector<int> y (n);
        for (int i=0; i<n; i++){
            cin>>x[i]>>y[i];
        }
        x1 = *min_element(x.begin(), x.end());
        x2 = *max_element(x.begin(), x.end());
        y1 = *min_element(y.begin(), y.end());
        y2 = *max_element(y.begin(), y.end());
        for (int i=0; i<n; i++){
            if (!(x[i]==x1 || x[i]==x2 || y[i]==y1 || y[i]==y2)){
                flag=1;
                break;
            }
        }
        if (flag==1)
            cout<<"NO"<<endl;
        else
            cout<<"YES"<<endl;
        flag = 0;
        x.clear();
        y.clear();
    }
    return 0;
}