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

q = int(raw_input().strip())
for i in xrange(q):
    n = int(raw_input().strip())
    x_min = float("inf")
    y_min = float("inf")
    x_max = float("-inf")
    y_max = float("-inf")
    points = list()
    for i in xrange(n):
        x, y = raw_input().strip().split(' ')
        x, y = [int(x), int(y)]
        points.append((x, y))
        if x < x_min:
            x_min = x
        if x > x_max:
            x_max = x
        if y < y_min:
            y_min = y
        if y > y_max:
            y_max = y

    res = 'YES'
    for x, y in points:
        if x != x_min and x != x_max and y != y_min and y != y_max:
            res = 'NO'
            break
        elif (((x == x_min or x == x_max) and (y < y_min or y > y_max)) or
             ((y == y_min or y == y_min) and (x < x_min or x > x_max))):
            res = 'NO'
            break

    print res