#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pdd pair<double,double>
#define FILL(a,x) memset(a,x,sizeof(a))
#define foreach( gg,ii ) for( typeof(gg.begin()) ii=gg.begin();ii!=gg.end();ii++)
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define sz(a) int((a).size())
#define N 100010
#define MAX 30
#define mod 1000000007
#define REP(i,a) for(int i=0;i<a;++i)
#define REPP(i,a,b) for(int i=a;i<b;++i)
#define all(a) a.begin(),a.end()
const ll INF = 1e18+1;

vector <int> vx,vy;
int xc[N],yc[N];

int main()
{
	int n,q,x,y,cntx,cnty;
	scanf("%d",&q);
	while(q--)
	{
		scanf("%d",&n);
		cntx=0,cnty=0;
		vx.clear();
		vy.clear();
		REP(i,n)
		{
			scanf("%d%d",&x,&y);
			vx.pb(x);
			vy.pb(y);
			xc[i]=x;
			yc[i]=y;
		}
		sort(all(vx));
		sort(all(vy));
		REP(i,sz(vx))
			REPP(j,i+1,sz(vx))
				REP(k,sz(vy))
					REPP(l,k+1,sz(vy))
					{
						cntx=0;
						REP(o,n)
						{
							if (((xc[o]==vx[i]||xc[o]==vx[j])&&(yc[o]>=vy[k]&&yc[o]<=vy[l]))||((yc[o]==vy[k]||yc[o]==vy[l])&&(xc[o]>=vx[i]&&xc[o]<=vx[j]))) cntx++;
							else break;
						}
						if (cntx==n)
						{
							//printf("%d %d %d %d\n",vx[i],vx[j],vy[k],vy[l]);
							cnty=1;
							break;
						}
					}
		if (cnty) printf("YES\n");
		else printf("NO\n");
	}
return 0;
}