q = int(input())
for _ in range(q):
    n = int(input())
    xs = []
    ys = []
    for _ in range(n):
        x,y = map(int,input().split())
        xs.append(x)
        ys.append(y)
    xmax = max(xs)
    ymax = max(ys)
    xmin = min(xs)
    ymin = min(ys)
    flag = True
    for i in range(n):
        if xs[i]!=xmax and xs[i]!=xmin and ys[i]!=ymax and ys[i]!=ymin:
            flag = False
            break
    if flag:
        print("YES")
    else:
        print("NO")