#include<bits/stdc++.h>
using namespace std;

#define _ ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
typedef long long ll;
#define mp make_pair
#define pb push_back
#define inf 1000000
#define c1(a) cin>>a
#define c2(a,b) cin>>a>>b
#define c3(a,b,c) cin>>a>>b>>c
#define c4(a,b,c,d) cin>>a>>b>>c>>d
#define cout(a) cout<<a<<endl


int main(void) {
	_
	int q;
	c1(q);
	for(int k=0; k<q; k++) {
		int n;
		c1(n);
		int x[n], y[n];
		int xmax(-1001), ymax(-1001), xmin(1001), ymin(1001);
		for(int i=0; i<n; i++) {
			int a,b;
			c2(a,b);
			x[i]=a;
			y[i]=b;
			xmax=max(xmax,a);
			xmin=min(xmin,a);
			ymax=max(ymax,b);
			ymin=min(ymin,b);
		}
		int flag(1);
		for(int i=0; i<n; i++) {
			if(x[i]!=xmax and x[i]!=xmin and y[i]!=ymin and y[i]!=ymax) {
				cout("NO");
				flag=0;
				break;
			}
		}
		if(flag) cout("YES");
	}
	return 0;
}