#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 M 1000000007
#define pp(n) printf("%lld\n",ll(n))
#define ps(n) printf("%lld ",ll(n))
#define pd(x,y) printf("%lld %lld\n",ll(x),ll(y))
#define is(n) scanf("%lld",&n)
#define max(x,y) max(ll(x),ll(y))
#define min(x,y) min(ll(x),ll(y))
#define inf LLONG_MAX
#define id(n,m) scanf("%lld%lld",&n,&m)
#define it(n,m,k) scanf("%lld%lld%lld",&n,&m,&k)
#define ss(s) scanf("%s",s)
#define cool 0
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define pll pair<ll,ll> 
#define db cout<<"######\n"
#define null(a) memset(a,0,sizeof(a))
#define neg(a) memset(a,255,sizeof(a))
typedef long double ld;
typedef long long int ll;
using namespace std;
ll i,j,k,z,t,n,m,sum,ans,x,y,maxm=0,minm=inf,l;
set<ll> sx,sy;
vector<ll> vx,vy;
pll a[15];
bool check(ll x0,ll x1,ll y0,ll y1)
{
ll i;	
if(x1<x0)
swap(x1,x0);
if(y1<y0)
swap(y1,y0);
	for(i=0;i<n;i++)
	{
			 if(a[i].F==x1 and a[i].S>=y0 and a[i].S<=y1) continue;
		else if(a[i].F==x0 and a[i].S>=y0 and a[i].S<=y1) continue;
		else if(a[i].S==y1 and a[i].F>=x0 and a[i].F<=x1) continue;
		else if(a[i].S==y0 and a[i].F>=x0 and a[i].F<=x1) continue;
		else
		return false;
	}
	
	return true;
}
int main()
{
	is(t);
	while(t--)
	{
		bool flag=false;
		is(n);
		
		up(0,n,i)
		{
			id(a[i].F,a[i].S);
			vx.pb(a[i].F);
			vy.pb(a[i].S);
		}
		
		
		
		up(0,vx.size(),i)
		up(0,vx.size(),j)
		up(0,vy.size(),k)
		up(0,vy.size(),l)
		if(check(vx[i],vx[j],vy[k],vy[l]))
		flag=true;
		
		if(flag)
		puts("YES");
		else
		puts("NO");
	}
	
}