#include<bits/stdc++.h>
using namespace std;
#define fs first
#define sc second
#define MAX 100000
#define pb push_back
#define mp make_pair
#define INF (1LL<<62)
#define MOD 1000000007
typedef long long Int;
typedef pair<Int,Int> pii;
typedef vector<Int> vi;
typedef vector<pii> vii;

int main()
{
    Int Q,x,y,n;
    cin>>Q;
    while(Q--)
    {
        cin>>n;
        
        vii v;
        Int ax=INF,bx=-10010,ay=INF,by=-10010;
        for(int i=1;i<=n;i++)
        {
            cin>>x>>y;
            v.pb(mp(x,y));
            ax=min(ax,x);
            bx=max(bx,x);
            
            ay=min(ay,y);
            by=max(by,y);
            
        }
        bool flag=false;
         for(int i=0;i<n;i++)
        {
           if(v[i].fs==ax||v[i].fs==bx||v[i].sc==ay||v[i].sc==by)
               continue;
             else
             {
                 cout<<"NO\n";
                 flag=true;
                 break;
             }
            
        }
        if(!flag)
            cout<<"YES\n";
        
        
        
    }
    
    return 0;
}