/* ta yag odo batorshihiin code harj bn */

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;

const ll MOD = 1000000009ll;
const ll INFl = 9223372036854775807ll;
const int inf = (1 << 30) - 1;

#define ff first
#define ss second
#define pb push_back
#define _N 100005
#define mk make_pair

ll power(ll x, ll y, ll z) { ll t = 1; while (y > 0) { if (y % 2) { t = (t * x) % z; } x = (x * x) % z; y /= 2; } return t; }

int movex[4] = {0, 1, -1, 0};
int movey[4] = {1, 0, 0, -1};

int n;



const int af = 10000;

bool M[af * 2 + 123][af * 2+123];
int X[af * 3] = {0}, Y[af * 3] = {0};

int main () {
//	freopen ("std.in", "r", stdin);
//	freopen ("std.out", "w", stdout);
	int q, i, j;
	int x, y;
	scanf ("%d", &q);
	while (q --) {
		scanf ("%d", &n);
		int ymin = af, xmin = af;
		int xmax = -af, ymax = -af;
		memset (M, 0, sizeof M);
		memset (X, 0, sizeof X);
		memset (Y, 0, sizeof Y);
		for (i = 0; i < n; i ++) {
		scanf ("%d%d", &x, &y);
			x += af; y += af;
			X[x] ++; Y[y] ++;
			M[x][y] = 1;
			ymin = min (ymin, y);
			ymax = max (ymax, y);
			xmin = min (xmin, x);
			xmax = max (xmax, x);
		}
		if (ymin == ymax || xmin == xmax) {
			printf ("YES\n"); continue;
		}
		int ans;
		ans = Y[ymin] + Y[ymax] + X[xmin] + X[xmax];
		ans -= M[xmin][ymin];
		ans -= M[xmin][ymax];
		ans -= M[xmax][ymin];
		ans -= M[xmax][ymax];
		if (ans == n) printf ("YES\n");
			else printf ("NO\n");
	}
	return 0;
}