#include <stdio.h>
#include <iostream>
#include <stdlib.h>
#include <string>
#include <string.h>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <assert.h>
#include <algorithm>
#include <iomanip>
#include <time.h>
#include <math.h>
#include <bitset>

#pragma comment(linker, "/STACK:256000000")

using namespace std;

typedef long long int int64;
typedef long double double80;

const int INF = (1 << 29) + 5;
const int64 LLINF = (1ll << 59) + 5;
const int MOD = 1000 * 1000 * 1000 + 7;

pair<int, int> arr[12];

int main()
{
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);

	int q;

	cin >> q;

	int order[10];
	while (q--)
	{
		int n;
		cin >> n;
		for (int i = 0; i < n; ++i)
			cin >> arr[i].first >> arr[i].second;

		arr[n] = arr[0];
		for (int i = 0; i < n; ++i)
			order[i] = i;
		
		bool good = false;
		
		int mx = -INF, my = -INF, mix = INF, miy = INF;

		for (int i = 0; i < n; ++i)
		{
			mx = max(mx, arr[i].first);
			mix = min(mix, arr[i].first);
			my = max(my, arr[i].second);
			miy = min(miy, arr[i].second);
		}

		//cout << mix << " " << mx << " " << miy << " " << my << endl;


		good = true;

		for (int i = 0; i < n; ++i)
		{
			if (arr[i].first == mx || arr[i].first == mix)
			{
				good &= (arr[i].second <= my && arr[i].second >= miy);
			}
			else if (arr[i].second == my || arr[i].second == miy)
			{
				good &= (arr[i].first <= mx && arr[i].first >= mix);
			}
			else
			{
				good = false;
			}
		}

		cout << (good ? "YES\n" : "NO\n");
	}

	fclose(stdin);
	fclose(stdout);

	return 0;
}