#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#define ll long long
using namespace std;
long long maxx,maxy,minx,miny;
int onrect(long long a,long long b){
    if(b==miny || b==maxy || a==maxx || minx==a)
        return 1;
    return 0;
}
long long x[20],y[20];
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    long long q,n,inp,i,j;
    cin>>q;
    string flag;
    while(q--){
        maxx=maxy=-100001;
        minx=miny=100001;
        cin>>n;
        for(i=0;i<n;i++)
        {
            cin>>x[i]>>y[i];
            maxx=max(maxx,x[i]);
            maxy=max(maxy,y[i]);
            minx=min(minx,x[i]);
            miny=min(miny,y[i]);
        }
        flag="YES";
        for(i=0;i<n;i++){
            if(!onrect(x[i],y[i]))
                flag="NO";
        }
        cout<<flag<<endl;
    }
    return 0;
}