#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

int main()
{
ll i,w,j,k,l,m,n,x,y,z,ans=0,c=0,t,x1,x2,y1,y2,z1,z2,z3,z4;
cin>>t;
while(t--)
{
    pair<ll,ll> p[50];
    cin>>n;
    int f=1;
    for(i=0;i<n;i++)
        {
        cin>>p[i].first>>p[i].second;
    }
    x1=INT_MAX,x2=INT_MAX,y1=-1000000000000,y2=-1000000000000;
    for(i=0;i<n;i++)
        {
        if(x1>p[i].first)
            {
            x1=p[i].first;
            z1=i;
        }
       if(x2>p[i].second)
           {
        x2=p[i].second;
           z2=i;
       }
         if(y1<p[i].first)
           {
             y1=p[i].first;
             z3=i;
           
       }
         if(y2<p[i].second)
           {
             y2=p[i].second;
             z4=i;
           
       }
}
    if(p[z1].second!=p[z3].second&&p[z2].first!=p[z4].first)
        {
        cout<<"NO"<<endl;
    }
  //  cout<<x1<<" "<<x2<<" "<<y1<<" "<<y2<<endl;
    for(i=0;i<n;i++)
        {
        x=p[i].first;
        y=p[i].second;
        if(x==x1&&y<=y2&&y>=x2)
            continue;
        if(x==y1&&y<=y2&&y>=x2)
            continue;
        if(x==x2&&y<=y1&&y>=x1)
            continue;
        if(x==y2&&y<=y1&&y>=x1)
            continue;
      //  cout<<i<<endl;
        f=0;
    }
    if(f)
        cout<<"YES"<<endl;
    else
        cout<<"NO"<<endl;
}

return 0;
}