def solve(min_x, max_x, min_y, max_y, points):
    #print(min_x, max_x, min_y, max_y)
    for x, y in points:
        #print(x, y)
        if min_x < x < max_x and min_y < y < max_y:
            return "NO"
    return "YES"

t = int(input())
for _ in range(t):
    n = int(input())
    points = []
    min_x, max_x, min_y, max_y = None, None, None, None
    for i in range(n):
        x, y = map(int, input().split())
        points.append((x, y))
        if min_x == None or x < min_x:
            min_x = x
        if max_x == None or x > max_x:
            max_x = x
        if min_y == None or y < min_y:
            min_y = y
        if max_y == None or y > max_y:
            max_y = y
    print(solve(min_x, max_x, min_y, max_y, points))