#include<bits/stdc++.h>
using namespace std;
#define f first
#define s second
const int N=15; pair<int,int> p[N];
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q,n; cin>>q;
    while(q--){
        cin>>n;
        int minx=INT_MAX,maxx=INT_MIN,miny=INT_MAX,maxy=INT_MIN;
        for(int i=0;i<n;i++) {
         cin>>p[i].f>>p[i].s;
         minx=min(minx,p[i].f); maxx=max(maxx,p[i].f);
         miny=min(miny,p[i].s); maxy=max(maxy,p[i].s);   
        }
        bool pos=1;
        for(int i=0;i<n;i++){
          int x=p[i].f,y=p[i].s;
            if(x==minx || x==maxx){
              if(y<miny|| y>maxy) { pos=0; break;}
            }
            else if(y==miny || y==maxy){
              if(x<minx || x>maxx){ pos=0; break;}  
            }
            else {pos=0; break;}
        }
        if(pos) cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
    return 0;
}