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


int main() {
    int q;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        int x[n], y[n];
        int x1=7777777, x2=-7777777, y1=7777777, y2=-7777777;
        for(int i=0; i<n; i++) {
            cin>>x[i]>>y[i];
            x1=min(x1, x[i]);
            x2=max(x2, x[i]);
            y1=min(y1, y[i]);
            y2=max(y2, y[i]);
        }
        
        bool flag=true;
        for(int i=0; i<n; i++){
            if(x[i]==x1);
            else if(x[i]==x2);
            else {
                if(y[i]==y1);
                else if(y[i]==y2);
                else {
                    flag=false;
                    break;
                }
            }
        }
        if(flag) cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
    return 0;
}