#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 flag=0;
        int maxx=100000,maxy=100000,minx=-100000,miny=-100000;
        while(n--){
                int x,y;
            cin>>x>>y;
            if(x<minx)
                minx=x;
            if(x>maxx)
                maxx=x;
            if(y<miny)
                miny=y;
            if(y>maxy)
                maxy=y;
            
            if(x!=maxx || x!=minx){
                   if(y!=maxy || y!=miny)
                       flag=1;
            }
            if(y!=maxy || y!=miny){
                   if(x!=maxx || x!=minx)
                       flag=1;
            }
            
        }
        if(flag)
            cout<<"NO";
        else
            cout<<"YES";
    }
    return 0;
}