#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;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        int arrx[n],arry[n];
        cin>>arrx[0]>>arry[0];
        int minx=arrx[0],maxx=arrx[0],miny=arry[0],maxy=arry[0];
        for(int i=1;i<n;i++){
            cin>>arrx[i]>>arry[i];
            if(arrx[i]<minx)
                minx=arrx[i];
            else if(arrx[i]>maxx)
                maxx=arrx[i];
            if(arry[i]<miny)
                miny=arry[i];
            else if(arry[i]>maxy)
                maxy=arry[i];
            
        }
        int flagx=0,flagy=0,flag=0;
        for(int i=0;i<n;i++){
            flagx=0;
            flagy=0;
            if(arrx[i]==maxx || arrx[i]==minx){
                if(arry[i]<miny || arry[i]>maxy)
                    flagx=1;
            }
            else
                flagx=1;
            if(arry[i]==maxy || arry[i]==miny){
                if(arrx[i]<minx || arrx[i]>maxx)
                    flagy=1;
            }
            else
                flagy=1;
            if(flagx && flagy){
                flag=1;
                break;
            }
        }
        if(flag==0)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
        
    }
    return 0;
}