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


int main() {
    int q,n,flag=0,i,x1=INT_MIN,x2=INT_MAX,y1=INT_MIN,y2=INT_MAX;
    cin>>q;
    while(q--){
        cin>>n;
        int x[n],y[n];
        x1=INT_MIN;
        x2=INT_MAX;
        y1=INT_MIN;
        y2=INT_MAX;
        flag=0;
        for(i=0;i<n;i++){
            cin>>x[i]>>y[i];
            x1 = max(x1,x[i]);
            x2 = min(x2,x[i]);
            y1 = max(y1, y[i]);
            y2 = min(y2, y[i]);
        }
        for(i=0;i<n && flag==0;i++){
            if( x[i] == x2 && y[i]>=y2 && y[i] <= y1 );
            else if( x[i] == x1 && y[i]>=y2 && y[i] <= y1 );
            else if( y[i] == y1 && x[i]>=x2 && x[i] <= x1 );
            else if( y[i] == y2 && x[i]>=x2 && x[i] <= x1 );
            else 
                flag = 1;
        }
        if(flag==1)
            cout<<"NO"<<endl;
        else
            cout<<"YES"<<endl;
    }
    return 0;
}