q = int(input())

for _ in range(q):
    n = int(input())
    nums = [[int(x) for x in input().strip().split()] for i in range(n)]
    min_x = min([nums[x][0] for x in range(n)])
    max_x = max([nums[x][0] for x in range(n)])
    min_y = min([nums[x][1] for x in range(n)])
    max_y = max([nums[x][1] for x in range(n)])
    good = True
    for x, y in nums:
        if x == min_x and y >= min_y and y <= max_y:
            pass
        elif x == max_x and y >= min_y and y <= max_y:
            pass
        elif y == min_y and x >= min_x and x <= max_x:
            pass
        elif y == max_y and x >= min_x and x <= max_x:
            pass
        else:
            good = False
    if good:
        print('YES')
    else:
        print('NO')