# Enter your code here. Read input from STDIN. Print output to STDOUT
q = int(raw_input().strip())
for _ in xrange(q):
    n = int(raw_input().strip())
    points = []
    for _ in xrange(n):
        x, y = map(int, raw_input().strip().split(' '))
        points.append((x, y))
    
    y_points = map(lambda (x, y) : y, points)
    top_line = max(y_points)
    bottom_line = min(y_points)
    x_points = map(lambda (x, y) : x, points)
    left_line = min(x_points)
    right_line = max(x_points)
    
    printed = False
    for x, y in points:
        if x != left_line and x != right_line and y != top_line and y != bottom_line:
            print('NO')
            printed = True
            break
    if not printed:
        print('YES')