# Enter your code here. Read input from STDIN. Print output to STDOUT
queries = gets.strip.to_i
queries.times do
    num_points = gets.strip.to_i
    points_array= []
    num_points.times do 
        point = gets.split(' ')
        points_array.push(point)
    end
    x_values = []
    y_values = []
    points_array.each do |point|
        x_values.push(point[0])
        y_values.push(point[1])
    end
    if x_values.uniq.count > 2 || y_values.uniq.count > 2
        print "NO"
    else
        print "YES"
    end
end