#define _CRT_SECURE_NO_WARNINGS
#pragma comment(linker, "/stack:16777216")
#include <string>
#include <vector>
#include <map>
#include <list>
#include <iterator>
#include <set>
#include <queue>
#include <iostream>
#include <sstream>
#include <stack>
#include <deque>
#include <cmath>
#include <memory.h>
#include <cstdlib>
#include <cstdio>
#include <cctype>
#include <algorithm>
#include <utility>
#include <assert.h>
#include <time.h>


#include <fstream>
#include <sys/stat.h>
#include <stdlib.h>
#include <stdio.h>
using namespace std;

#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, b, a) for(int i=(b)-1;i>=(a);--i)
#define FILL(A,value) memset(A,value,sizeof(A))
#define ALL(V) V.begin(), V.end()
#define SZ(V) (int)V.size()
#define PB push_back
#define MP make_pair
#define Pi 3.14159265358979

typedef long long Int;
typedef unsigned long long UInt;
typedef vector<int> VI;
typedef pair<int, int> PII;

const int INF = 1000000000;
const int MAX = 500007;
const int MAX2 = 1000000;
const int MAXD = 20;
const int BASE = 1000000007;
const int MOD = 1000000007;


int main() {

	//freopen("in.txt" , "r" , stdin);


	int q;
	cin >> q;
	FOR(qq,0,q)
	{
		int n;
		cin >> n;
		vector<PII> A;
		int minY = INF;
		int maxY = -INF;
		int minX = INF;
		int maxX = -INF;

		FOR(i,0,n)
		{
			int x , y;
			cin >> x >> y;

			minY = min(minY , y);
			maxY = max(maxY , y);
			minX = min(minX , x);
			maxX = max(maxX , x);

			A.push_back(MP(x , y));
		}

		bool ok = 1;
		FOR(i,0,n)
		{
			if (A[i].first == minX || A[i].first == maxX || A[i].second == minY || A[i].second == maxY)
			{

			}
			else
			{
				ok = 0;
			}
		}
		cout << (ok ? "YES" : "NO") << endl;
	}

    return 0;
}