#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
#define mi -1000000
#define mm 1000000

int main() {
    int t;
    cin>>t;
    while(t--){
        int a;
        cin>>a;
        int x1=mm,x2=mi,y1=mm,y2=mi,x,y;
        int X[a],Y[a];
        bool flag=true;
        for(int i=0;i<a;i++){
            cin>>X[i]>>Y[i];
            if(X[i]>x2)
                x2=X[i];
            if(X[i]<x1)
                x1=X[i];
            if(Y[i]>y2)
                y2=Y[i];
            if(Y[i]<y1)
                y1=Y[i];
        }
        //cout<<x1<<y1<<x2<<y2;
        for(int i=0;i<a;i++){
            if(X[i]!=x1 && Y[i]!=y1 && X[i]!=x2 && Y[i]!=y2){
                    flag=false;
                    break;
            }
        }
        //if(x1==x2 || y1==y2) flag=false;
        if(!flag) cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
    }
    return 0;
}