//Bismillahir Rahmanir Rahim
#include<bits/stdc++.h>
using namespace std;
#define pb      push_back
#define _       ios_base::sync_with_stdio(false);
#define ct      cin.tie(NULL);
#define ll      long long
#define eps     1e-10
#define ms(n,i) memset(n,i,sizeof n)
#define pi      2*acos(0)
#define inf     1<<30
#define fr(i,n) for(i=0;i<n;i++)
#define fr1(i,n)for(i=1;i<=n;i++)
#define abs(x)  ((x<0)?-(x):x)
#define MAX 30005
#define sp(i)      cout<<fixed<<setprecision(i)
//STL
typedef      vector<int> vi;
typedef      vector<ll> vl;
typedef      pair<int,int>ii;
#define mp      make_pair
#define ft      first
#define sd      second
#define IT      iterator
#define pr(c,x) ((c).find(x)!=(c).end())
#define sz(a) int((a).size())
#define all(c)  c.begin(), c.end()
#define tr(c,i) for(__typeof((c).begin()) i=(c).begin();i!=c.end();i++)
#define vpresent(c,x) (find(all(c),x)!=(c).end())
#define eb      emplace_back
//


//input output
#define sf      scanf
#define pf      printf

#define sf1(a)  sf("%d",&a)
#define sf2(a,b)  sf("%d%d",&a,&b)
#define sf3(a,b,c)   sf("%d%d%d",&a,&b,&c)

#define nl cout<<"\n"
//eof

//seg tree
#define lc      (s+e)>>1
#define rc      (lc)+1
#define Ln      n<<1
#define Rn      (Ln)|1
//end of seg tree




//int dx[]={1,0,-1,0};int dy[]={0,1,0,-1}; //4 Direction
//int dx[]={1,1,0,-1,-1,-1,0,1};int dy[]={0,1,1,1,0,-1,-1,-1};//8 direction
//int dx[]={2,1,-1,-2,-2,-1,1,2};int dy[]={1,2,2,1,-1,-2,-2,-1};//Knight Direction
//int dx[]={2,1,-1,-2,-1,1};int dy[]={0,1,1,0,-1,-1}; //Hexagonal Direction

vector<ii> w;

int main()
{
       // freopen("D:\\Coding\\in.txt","r",stdin);
       // freopen("D:\\Coding\\out.txt","w",stdout);
    int q,n,i,tot;
    ii mn,mx,in;
    mn=ii(100000,100000);
    mx=ii(-100000,-100000);

    sf1(q);
    while(q--)
    {
        mn=ii(100000,100000);
    mx=ii(-100000,-100000);
        sf1(n);
        w.clear();
        fr(i,n)
        {
            sf2(in.ft,in.sd);
            w.pb(in);
            mn.ft=min(mn.ft,in.ft);
            mn.sd=min(mn.sd,in.sd);

            mx.ft=max(mx.ft,in.ft);
            mx.sd=max(mx.sd,in.sd);
        }
        tot=0;
        fr(i,n)
        {
            if(((w[i].ft==mn.ft||w[i].ft==mx.ft)&&w[i].sd>=mn.sd&&w[i].sd<=mx.sd)||((w[i].sd==mn.sd||w[i].sd==mx.sd)&&w[i].ft>=mn.ft&&w[i].ft<=mx.ft))
                tot++;
            else break;
        }
        if(tot==n)cout<<"YES";
        else cout<<"NO";
        nl;

    }

    return 0;
}