def solve(xs, ys):
    for (x, y) in zip(xs, ys):
        if x > min(xs) and x < max(xs):
            if y > min(ys) and y < max(ys):
                return "NO"
    
    return "YES"

q = int(input())
for _ in range(q):
    n = int(input())
    
    xs = []
    ys = []
    for i in range(n):
        x, y = list(map(int, input().strip().split(" ")))
        xs.append(x)
        ys.append(y)
    result = solve(xs, ys)
    print(result)