# Enter your code here. Read input from STDIN. Print output to STDOUT
q = int(raw_input())

for qi in xrange(q):
    n = int(raw_input())
    lst = []
    for i in xrange(n):
        inp = map(int,raw_input().split())
        lst.append((inp[0],inp[1]))
        
    if(n<=3):
        print "YES"
    else:
        print "NO"