//ALL HAIL MEGATRON

using namespace std;

#include<bits/stdc++.h>

#define wl(n) while(n--)
#define fl(i,a,b) for(i=a; i<b; i++)
#define rev(i,a,b) for(i=a; i>=b; i--)
#define scan(n) scanf("%d", &n)
#define scans(s) scanf("%s", s)
#define scanc(c) scanf("%c", &c)
#define scanp(f) scanf("%f", &f)
#define scanll(l) scanf("%lld", &l)
#define scanllu(u) scanf("%llu", &u)
#define print(n) printf("%d\n", n)
#define prints(s) printf("%s\n", s)
#define printc(c) printf("%c\n", c)
#define printp(f) printf("%f\n", f)
#define printll(l) printf("%lld\n", l)
#define printllu(u) printf("%llu\n", u)
#define nline printf("\n")
#define mclr(strn) strn.clear()
#define ignr cin.ignore()
#define MOD 1000000007
#define ll long long int
#define u64 unsigned long long int
#define PB push_back

int main()
{
	int q;
	scan(q);
	wl(q)
	{
		ll n,i,x,y;
		scanll(n);
		vector<pair<ll,ll> > v;
		ll x1 = MOD, x2 = -MOD, y1 = MOD, y2 = -MOD;
		fl(i,0,n)
		{
			scanll(x);
			scanll(y);
			
			x1 = min(x,x1);
			x2 = max(x2,x);

			y1 = min(y1,y);
			y2 = max(y2,y);
			v.PB({x,y});
		}
		//sort(v.begin(), v.end());

		
		bool flag = 0;

		fl(i,0,n)
		{
			if(v[i].first>x1 && v[i].first<x2 && (v[i].second!=y1 && v[i].second!=y2))
			{
				flag = 1;
				break;
			}
		}

		if(!flag)
			printf("YES\n");
		else
			printf("NO\n");

	}
	return 0;
}