q = int(input())
for i in range(q):
    n = int(input())
    x = []
    y = []
    for j in range(n):
        dot = list(map(int, input().split()))
        x.append(dot[0])
        y.append(dot[1])
    max_x = max(x)
    min_x = min(x)
    min_y = min(y)
    max_y = max(y)
    result = True
    for k in range(len(x)):
        if x[k]!=min_x and x[k]!=max_x and y[k]!=min_y and y[k]!=max_y:
            result = False
            break
    if result:
        print('YES')
    else:
        print('NO')