#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <climits>
using namespace std;
float dist(int a,int b,int c,int d);

int main() {
    int q;
    cin>>q;
    while(q--)
    {
       
        int maxx,maxy;
        maxx = maxy = INT_MIN;
        int minx,miny;
        minx = miny = 10005;
        int n;
        cin>>n;
        int a[n][2];
        for(int i=0;i<=n-1;i++)
            cin>>a[i][0]>>a[i][1];
        for(int i=0;i<=n-1;i++)
            {
            if(maxx<a[i][0])
                maxx = a[i][0];
            if(minx>a[i][0])
                minx = a[i][0];
            if(maxy<a[i][1])
                maxy = a[i][1];
            if(miny>a[i][1])
                miny = a[i][1];
            }
        
       
    int flag = 0;
        for(int i=0;i<=n-1;i++)
            { if(a[i][0]==maxx||a[i][0]==minx||a[i][1]==maxy||a[i][1]==miny)
                {
            if(a[i][0]==maxx||a[i][0]==minx)
                {
                if(a[i][1]>maxy||a[i][1]<miny)
                {flag =1;
                break;}
            }
            if(a[i][1]==maxy||a[i][1]==miny)
                {
                if(a[i][0]>maxx||a[i][0]<minx)
                    {
                    flag =1;
                break;
                }
            }}
            else {flag=1;break;}
        }
        if(flag==1)
            cout<<"NO\n";
        else cout<<"YES\n";
    }/* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}