# Enter your code here. Read input from STDIN. Print output to STDOUT

q = input()

for i in range(q):
    z = input()
    _x = []
    _y = []
    
    for j in range(z):
        x, y = map(int, raw_input().split())
        _x.append(x)
        _y.append(y)
        
    check = False
    
    for a,b in zip(_x, _y):
        if min(_x) < a < max(_x) and min(_y) < b < max(_y):
                    print "NO"
                    check = True
                    break

    if not check:
        print "YES"