from fileinput import input


data = input()

for _ in range(int(next(data))):
    n = int(next(data))
    points = []
    for i in range(n):
        x, y = map(int, next(data).split())
        points.append((x, y))

    min_x = min([x for x, y in points])
    max_x = max([x for x, y in points])
    min_y = min([y for x, y in points])
    max_y = max([y for x, y in points])

    valid = True
    for x, y in points:
        edges = [min_x, min_y, max_x, max_y]
        if x not in edges and y not in edges:
            valid = False
            break
    if valid:
        print('YES')
    else:
        print('NO')