q = int(input().strip())  # num queries
for x in range(q):
    numPoints = int(input().strip())
    result = 1  # assume pass

    x_set = set()
    y_set = set()
    for y in range(numPoints):
        xx, yy = [int(vv) for vv in input().strip().split()]
        x_set.add(xx)
        y_set.add(yy)

    if len(x_set) > 2 and len(y_set) > 2:
        result = 0 # fail - inner point
    if len(x_set) == 1 or len(y_set) == 1:
        result = 0 # fail - degenerate
    
    if result:
        print("YES")
    else:
        print("NO")