# Enter your code here. Read input from STDIN. Print output to STDOUT

def lies(point, x0, x1, y0, y1)
    (point[0] == x0 || point[0] == x1) || (point[1] == y0 || point[1] == y1)
end

q = gets.to_i
for i in 1..q do 
    t = gets.to_i
    points = []
    for j in 1..t do
        x, y = gets.split(' ').map(&:to_i)
        points << [x, y]        
    end        
    
    pp = points.sort {|p1, p2| (p1[0] <=> p2[0])}
    x0 = pp.first[0]
    x1 = pp.last[0]

    pp = points.sort {|p1, p2| (p1[1] <=> p2[1])}
    y0 = pp.first[1]
    y1 = pp.last[1]
   
#    p "#{x0} #{x1} #{y0} #{y1}"
    
    fall = true
    pp.each do |point|
        if !lies(point, x0, x1, y0, y1)
            fall = false
        end
    end
    
    printf("%s\n", fall ? "YES" : "NO")
end