import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        
        int Q = in.nextInt();

        for(int q = 0; q < Q; q++) {
            int n = in.nextInt();

            int[] X = new int[n];
            int[] Y = new int[n];
            for (int i = 0; i < n; i++) {
                X[i] = in.nextInt();
                Y[i] = in.nextInt();
            }

            Arrays.sort(X);
            Arrays.sort(Y);

            int countX = 0;
            for (int i = 1; i < n; i++) {
                if (X[i - 1] != X[i]) {
                    countX++;
                }
            }

            int countY = 0;
            for (int i = 1; i < n; i++) {
                if (Y[i - 1] != Y[i]) {
                    countY++;
                }
            }

            if ((countX == 1 && countY != 0) || (countY == 1 && countX != 0) || n == 1 || n == 2) {
                System.out.println("YES");
            } else {
                System.out.println("NO");
            }
        }
    }
}