#include<bits/stdc++.h>
#define up(j,k,i) for(i=j;i<k;i++)
#define down(j,k,i) for(i=j;i>k;i--)
#define pp(n) printf("%lld\n",n)
#define is(n) scanf("%lld",&n)
#define ips(n) scanf("%lld",n)
#define ss(s) scanf("%s",s)
#define cool 0
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define f(i) cout<<i<<endl;
#define pll pair<lld,lld> 
#define pi acos(-1)
#define ds(n,m) scanf("%lld %lld",&n,&m)
#define ts(n,m,k) scanf("%lld %lld %lld",&n,&m,&k)
typedef long double ld;
typedef long long int lld;
using namespace std;
const lld M =1e18+7;
const lld mod=1e9+7;
const lld infi =1e18+7;
lld x[100],y[100];
lld check(lld x1,lld x2,lld y1,lld y2,lld n)
{
  lld i;
  x1=x[x1];
  y1=y[y1];
  x2=x[x2];
  y2=y[y2];
  if(x1>x2)swap(x1,x2);
  if(y1>y2)swap(y1,y2);
  up(0,n,i)
  {
    if(x[i]==x1)
    {
      if(y[i]>y2||y[i]<y1)return 0;
    }
    else if(x[i]==x2)
    {
      if(y[i]>y2||y[i]<y1)return 0;
    }
    else if(y[i]==y1)
    {
      if(x[i]>x2||x[i]<x1)return 0;
    }
    else if(y[i]==y2)
    {
      if(x[i]>x2||x[i]<x1)return 0;
    }
    else
      return 0;
  }
  return 1;
}
int main()
{
    lld q;
    is(q);
    while(q--)
    {
      lld  n;
      is(n);
      lld i;
      up(0,n,i)
      {
        ds(x[i],y[i]);
      }
      lld x1,y1,x2,y2;
      lld flag=0;
      up(0,n,x1)
      {
        up(0,n,x2)
        {
          up(0,n,y1)
          {
            up(0,n,y2)
            {
              if(check(x1,x2,y1,y2,n))
              {
                flag=1;
                break;
              }
            }
            if(flag)break;
          }
          if(flag)break;
        }
        if(flag)break;
      }
      if(flag)cout<<"YES\n";
      else
      cout<<"NO\n";
    }
        
        return 0;
}