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

const int maxn = 50;
int n ;
pair < int , int > p[maxn];
vector < int > X , Y;

int main(int argc,char *argv[]){
	int T;
	cin >> T;
	while( T -- ){
		cin >> n;
		X.clear();
		Y.clear();
		int ok = 0;
		for(int i = 1 ; i <= n ; ++ i){
			cin >> p[i].first >> p[i].second;
			X.push_back( p[i].first );
			Y.push_back( p[i].second );
		}
		sort( X.begin() , X.end() );
		sort( Y.begin() , Y.end() );
		for(int i = 0 ; i < X.size() ; ++ i)
			for(int j = i ; j < X.size() ; ++ j)
				for(int k = 0 ; k < Y.size() ; ++ k)
					for(int v = k ; v < Y.size() ; ++ v){
						int x1 = X[i] , x2 = X[j];
						int y1 = Y[k] , y2 = Y[v];
						int find = 1;
						for(int g = 1 ; g <= n ; ++ g){
							int fs = 0;
							if( p[g].first == x1 && p[g].second <= y2 && p[g].second >= y1 ) fs = 1;
							if( p[g].first == x2 && p[g].second <= y2 && p[g].second >= y1 ) fs = 1;
							if( p[g].second == y1 && p[g].first <= x2 && p[g].first >= x1 ) fs = 1;
							if( p[g].second == y2 && p[g].first <= x2 && p[g].first >= x1 ) fs = 1;
							if( fs == 0 ){
								find = 0;
								break;
							}
						}
						ok |= find;
					}

		if( ok ) puts("YES");
		else puts("NO");
	}
	return 0;
}