#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i = (a); i <= (b); ++i)
#define FORD(i,a,b) for(int i = (a); i >= (b); --i)
#define RI(i,n) FOR(i,1,(n))
#define REP(i,n) FOR(i,0,(n)-1)
#define mini(a,b) a=min(a,b)
#define maxi(a,b) a=max(a,b)
#define mp make_pair
#define pb push_back
#define st first
#define nd second
#define sz(w) (int) w.size()
typedef vector<int> vi;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const int inf = 1e9 + 7;
const int maxN = 1e6 + 5;

int n, q, arrX[100], arrY[100];

bool check(int pos, int a, int b, int c, int d) {
	//cout<<arrX[pos]<<" "<<arrY[pos]<<" "<<a<<" "<<b<<" "<<c<<" "<<d<<endl;
	bool ans = arrX[pos] == a && arrY[pos] >= c && arrY[pos] <= d;
	ans = ans || (arrX[pos] == b && arrY[pos] >= c && arrY[pos] <= d);
	ans = ans || (arrY[pos] == c && arrX[pos] >= a && arrX[pos] <= b);
	ans = ans || (arrY[pos] == d && arrX[pos] >= a && arrX[pos] <= b);
	return ans;
}
int main() {
	scanf("%d",&q);
	while (q--) {
		scanf("%d",&n);
		int maxX = -inf, maxY = -inf, minY = inf, minX = inf;
		REP(i, n) {
			scanf("%d%d",&arrX[i], &arrY[i]);
			mini(minX, arrX[i]);
			maxi(maxX, arrX[i]);
			mini(minY, arrY[i]);
			maxi(maxY, arrY[i]);
		}
		
		bool ok = true;
		REP(i, n) {
			//cout<<"Here "<<i<<endl;
			bool ans = check(i, minX, maxX, minY, maxY);
			ok = ok && ans;
		}
		if (ok) printf("YES\n");
		else printf("NO\n");
	}
	return 0;
}