#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#define pp pair<int,int>
using namespace std;

int comparex(pp x,pp y)
    {
    if(x.first<y.first)
        return 1;
    else
        return 0;
}
int comparey(pp x,pp y)
    {
    if(x.second<y.second)
        return 1;
    else
        return 0;
}
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int q;
    cin>>q;
    while(q--)
        {
        int xc=0,yc=0,n,ans=1,minx=100000,maxx=-100000,miny=100000,maxy=-100000;
        cin>>n;
        pp a[n];
        for(int i=0;i<n;i++)
            {
            cin>>a[i].first>>a[i].second;
            minx=min(a[i].first,minx);
            maxx=max(a[i].first,maxx);
            miny=min(a[i].second,miny);
            maxy=max(a[i].second,maxy);
        }
        for(int i=0;i<n;i++)
            {
            if(a[i].second!=miny&&a[i].second!=maxy)
                {
                if(a[i].first!=minx&&a[i].first!=maxx)
                    ans=0;
            }
            if(a[i].first!=minx&&a[i].first!=maxx)
                {
                if(a[i].second!=miny&&a[i].second!=maxy)
                    ans=0;
            }
        }
        if(ans==0)
            cout<<"NO\n";
        else
            cout<<"YES\n";
    }
    return 0;
}