q = gets.strip.to_i
q.times do
    n = gets.strip.to_i
    ans = "NO"
    if n <= 4
        min_point = 10 ** 5
        max_point = -10 ** 5
        points = []
        n.times do
            x, y = gets.strip.split.map(&:to_i)
            min_point = [x, y, min_point].min
            max_point = [x, y, max_point].max
            points.push [x, y]
        end
        ans = "YES"
        points.each do |i, j|
            if i != min_point && i != max_point && j != min_point && j != max_point
                ans = "NO"
                break
            end
        end
    end
    puts ans
end