import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner in = new Scanner(System.in);
        int queries = in.nextInt();
        for(int i=0; i<queries; i++){
            int points = in.nextInt();
            Set<Integer> xset = new HashSet<Integer>();
            Set<Integer> yset = new HashSet<Integer>();
            for(int j=0; j<points; j++){
                int x = in.nextInt();
                xset.add(x);
                int y = in.nextInt();
                yset.add(y);
            }
            if(xset.size() > 2 || yset.size() > 2)System.out.println("NO");
            else System.out.println("YES");
        }
    }
}