#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;
        if(n<=2){cout<<"YES"; continue;}
        int x[n],y[n];
        for(int i=0; i<n; i++){cin>>x[i]>>y[i];}
        int a1,a2,b1,b2,c1,c2,d1,d2;
        if(x[0]>x[1]){a1=d1=x[0]; b1=c1=x[1]; } else {a1=d1=x[1]; b1=c1=x[0];}
        if(y[0]>y[1]){a2=b2=y[0]; c2=d2=y[1];} else {a2=b2=y[1]; c2=d2=y[0];}
        int a=c2,b=a2,c=b1,d=a1;
        bool flag=true;
        /*for(int i=2; i<n; i++){
            if(x[i]<c||x[i]>d){
                
            }
        }*/
        int g[5],h[5],l=0,m=0;
        g[0]=a1; g[1]=c1; h[0]=a2; h[1]=c2;
        for(int i=2; i<n; i++){
            if((x[i]!=g[0]&&x[i]!=g[1])&&(y[i]!=h[0]&&y[i]!=h[1])){flag=false; break;}
        }
        if(flag)cout<<"YES"<<endl; else cout<<"NO"<<endl;
    }
    return 0;
}