#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <cstring>
#include <deque>
#include <stack>
#include <stdio.h>
#include <map>
#include <set>
#include <time.h>
#include <string>
#include <fstream>
#include <queue>
#include <bitset>
#include <cstdlib>
#define X first
#define Y second
#define mp make_pair
#define pb push_back
#define pdd pair<double,double>
#define pii pair<ll,ll>
#define PI 3.14159265358979323846
#define MOD 1000000007
#define MOD2 1000000009
#define INF ((ll)1e+18)
#define x1 fldgjdflgjhrthrl
#define x2 fldgjdflgrtyrtyjl
#define y1 fldggfhfghjdflgjl
#define y2 ffgfldgjdflgjl
#define N 202100
#define SUM 23423
#define MAG 333
typedef long long ll;
typedef long double ld;
using namespace std;
ll i,j,n,k,l,m,x,y,tot, flag,h,r,ans,koko,z,nl,nr,maxx,maxy,minx,miny;
ll a[100500], b[100500], used[100500];
ll Abs(ll x)
{
	return x>0?x:-x;
}
int main() {
	//freopen("input.txt","r",stdin);
	//freopen("output.txt","w",stdout);
	ll tests;
	cin >> tests;
	while (tests--)
	{
		maxx=maxy = -MOD;
		minx=miny=MOD;
		cin >> n;
		for (i = 0; i < n; i++)
		{
			cin >> a[i] >> b[i];
			maxx = max(maxx, a[i]);
			maxy = max(maxy, b[i]);
			minx = min(minx, a[i]);
			miny = min(miny, b[i]);
		}
		ll flag = 1;
		for (i = 0; i < n; i++)
		{
			int cur = 0;
			if (a[i] == maxx && b[i] >= miny && b[i] <= maxy || a[i] == minx && b[i] >= miny && b[i] <= maxy ||
			b[i] == maxy && a[i] >= minx && a[i] <= maxx || b[i] == miny && a[i] >= minx && a[i] <= maxx)
				 cur = 1;
			flag &= cur;
		}
		if (flag)
		   cout << "YES" << endl;
		else
			cout << "NO" << endl;
	}
	return 0;
}